## Bladed Tutorial 04 – Basic Turbine Control

At wind speeds below rated, the goal is to capture as much energy as possible by

maximising the Power Coefficient. To do this, the tip speed ratio must be kept constant, at the Optimal value. This is only possible if the speed of the rotor can change as wind speed changes. To explain how this works, we need to show that when the power coefficient is

maximised, the ratio of generator torque to the generator speed squared has a

certain constant value. This constant value is called the Optimal Mode Gain. Equation (1) is our original mechanical power formula. Substituting the new

expressions for power and wind speed into equation 1, we have a new expression for

rotor torque in terms of rotor speed and tip speed ratio (equation 2)

Equation (1) is our original mechanical power formula. Substituting the new

expressions for power and wind speed into equation 1, we have a new expression

for rotor torque Constant rotor speed is achieved by pitching the blades progressively towards

feather as the wind speed rises. Pitching the blades ensures that despite the increasing wind speed, the net aerodynamic torque (about the rotor rotational axis) is held at a constant

value equal to the torque demand. With torque balanced, rotor speed – and therefore power output – both remain

constant. The usual way to pitch the blades is to use motors called pitch actuators, These pitch actuators turn the blades by powering a pinion which rotates the blade

root pitch bearing.

Wonderful Presentation, but i am just wondering how did you get the power of Gearbox ratio 3?