Civil Engineering Reference
In-Depth Information
FIGURE 5-15
Maximum power operation using power control scheme.
5.7
System Control Requirements
5.7.1
Speed Control
The rotor speed must be controlled for three reasons:
•
to capture more energy, as seen above.
•
to protect the rotor, the generator and the power electronic equip-
ment from overloading at high wind.
•
when the generator is disconnected accidentally or for a scheduled
event, losing the electrical load. Under this condition, the rotor speed
may run away, destroying it mechanically, if it is not controlled.
The speed control requirement of the rotor has five separate regions
(
Figure 5-16
)
:
1.
The cut-in speed at which the turbine starts producing power.
Below this speed, it is not efficient to turn on the turbine.
2.
The constant maximum C
region where the rotor speed varies
with the wind-speed variation to operate at the constant TSR cor-
responding to the maximum C
p
value.
p
3.
During high winds, the rotor speed is limited to an upper constant
limit based on the design limit of the system components. In the
constant speed region, the C
, and
the power increases at a lower rate than that in the first region.
is lower than the maximum C
p
p
4.
At still higher wind speeds, such as during a gust, the machine is
operated at constant power to protect the generator and the power
