ABB ACS800-67, System Description And Start-Up Manual

Page: 19 / 120

System description 19
Operational speed range of a typical wind turbine
Wind power increases cubically as wind speed increases:
where
P
w
wind power
air density
c
p
performance coefficient, tip speed ratio, pitch angle
A
r
rotor surface
v
w
wind speed.
There is a minimum wind speed at which power generation is reasonable (cut-in speed)
and a maximum speed at which the turbine can be operated safely (cut-out speed). At a
certain wind speed, the turbine controller must limit the rotor speed by changing the pitch
angle.
P
w
=
· A
r
· v
w
3
2
c
p
( , )
·