Civil Engineering Reference
In-Depth Information
FIGURE 5-16
Five regions of the turbine speed control.
electronics from overloading. This can be achieved by lowering the
rotor speed. If the speed is decreased by increasing electrical load,
the generator will be overloaded, defeating the purpose. To avoid
the generator overloading, some sort of brake, eddy current, or
other type, must be installed on the rotor.
5.
The cutout speed. Beyond certain wind speed, the rotor is shut off
producing power in order to protect the blades, the electrical gen-
erator, and other components of the systems.
5.7.2
Rate Control
The large rotor inertia of the blades must be taken into account in controlling
the speed. The acceleration and deceleration must be controlled to limit the
dynamic mechanical stress on the rotor blades and the hub, and the electrical
load on the generator and the power electronics. The instantaneous difference
between the mechanical power produced by the blades and the electrical
power delivered by the generator will change the rotor speed as follows:
J
d
dt
ω
P
me
−
=
(5-4)
ω
where J
= polar moment of inertia of the rotor
ω
= angular speed of the rotor
P
= mechanical power produced by the blades
m
P
= electrical power delivered by the generator.
e
