Environmental Engineering Reference
In-Depth Information
Cp & d i fferent fault effects
0.5
increasing sensor
bi as faul t
decreasing sensor
bi as faul t
0.4
0.3
3
0.2
λ
0
opt
0.1
0
-2
-0.1
2
4
6
8
10
12
14
λ
Fig. 7.9
The effect of sensor faults on power optimisation
in the scale-up sensor fault the control system slows down the rotor rotational
speed. This in turn may lead to the wind turbine entering the cut-off region.
• Fixed rotor speed sensor fault: the effect of this fault scenario differs based on
the fixed measured rotor speed (magnitude of stuck fault) and x ropt which in
turn depends on wind speed. If x ropt is lower than the fixed rotor speed mea-
surement then the controller will force the system to slow-down and this in turn
may lead to the cut-off rotational speed being reached. On the other hand, if
x ropt is higher than the fixed rotor speed then the controller will simply release
the turbine to rotate according to the available wind speed without control.
• Generator speed sensor bias fault: the sensor bias fault (decreasing or
increasing) affects the closed-loop performance of the wind turbine and hence
the wind power conversion efficiency. However, the expected effect of this
fault is probably less than the effect of the rotor speed sensor faults since the
generator speed signal is part of the feedback signal and not compared directly
with the reference optimal speed (i.e. not the objective signal).
• Generator torque bias fault: the effect of torque bias fault is similar to the
effect of the rotor speed sensor fault. In this fault scenario the inner-loop
generator controller minimises the difference between the T gr and the measured
generator torque T gm . In fact, T gm is not directly measured but obtained via soft
sensing. Therefore, any bias in this measurement results in driving the system
away from optimal operation. This results in a decrease of the wind turbine
power conversion efficiency. Fortunately, from a global control standpoint, this
fault appears as a scale actuator fault.
Figure 7.9 shows the effects of different fault scenarios on the optimal operation
of wind turbine.
Clearly, the generator and rotor speed sensor scaling faults emulate the effect of
the k opt uncertainty problem which arises in part due to wind turbine ageing and
Search WWH ::




Custom Search