Environmental Engineering Reference
In-Depth Information
blade deformation. Hence, even if the scaling fault is minor and does not lead to
structural damage, the detection and tolerance of this fault can lead to maintain the
harvested power at its optimal value.
Generally, the aim of all proposed FTC strategies in this chapter is to maintain
the same control law during both faulty and fault-free cases. Estimators are used to
simultaneously estimate the sensor fault signals and tolerate their effects on the
output signal delivered to the input of the controller.
While the proposal makes use of measured wind speed, the fault estimator in
these strategies is designed to be robust against the expected error between the
measured wind speed and the effective wind speed (EWS). This is because the
measured wind speed signal does not exactly represent the EWS signal.
7.6 T-S Fuzzy PMIO-Based Sensor FTC
This section describes a T-S fuzzy observer-based sensor FTC scheme designed to
optimise the wind energy captured in the presence of generator and rotor speed
sensor faults. To ensure good estimation of a wider than usual range of sensor
faults, the FTTC strategy utilises the fuzzy PMIO. The nominal fuzzy controller
remains unchanged during the faulty and fault-free cases. Although the proposed
strategy is dedicated to controlling the wind turbine within the low range of wind
speed (below rated wind speed), the proposed controller is useful as a supple-
mentary control to assist the pitch control system as a means of regulating the rotor
speed above the rated wind speed.
Recently, T-S fuzzy observer-based sensor FTC design has been proposed in
[
21
], see Fig.
7.10
. The method is based on evaluation of two residual signals
generated using the generalised observer concept of [
33
] to switch the estimation
from faulty to healthy observers with the assumption that no simultaneous sensor
faults are occur. It is clear that switching between two different observers produces
Wind
State
estimator(1)
Decision and
Switching
mechanism
Wind
Turbine
State
estimator(2)
Measured
wind speed
T-S Observer
based
T-S controller
+
-
Fig. 7.10
Generalised observer-based wind turbine AFTC
