Fig. 8 shows the mechanical power distribution of design
blade for variable wind speeds. Mechanical power turns into
electrical power as it goes through drive train and generator.
Since the goal of this research was to design a blade which
generates 3 MW of electrical power, the mechanical power
shown in Fig. 8 is always higher than electrical power due to
the system loss. At rated condition, mechanical power is predicted
a value of 3.31 MW along with 394.5 kN of thrust force
and it meets the criteria with condition of rated wind speed at
12.1 m/s. The wind power generation system controls generator
torque at below rated wind speed to continuously maintain
maximum efficiency. It also controls blade pitch to regulate
power output at the rated level in the region above rated wind
speed. To find proper blade pitch angles above rated wind
speed, numerical iteration is required for pitch angles at each
wind speed. After that, pitch schedule map shown in Fig. 9 is
made by acquiring pitch angle of the points where electrical
output becomes 3.0 MW.