where c
p1 ¼ 21, c
p 2 ¼ 125.2165, c
p 3 ¼ 9.7798, and c
p4 ¼ 0.0 0 6 8. This
function has a known maximum point C
p* ¼ 0 : 48 at the argument
value l
* ¼ 8.0 01.
This maximum C
p*
value gives the maximum captured power P
m
for a given wind speed v
w
. These facts can be exploited by solving
the TSR Equation (1) for um
and to obtain the optimal rotor speed: