Wind Turbines are optimized to produce maximum power output at the most portable wind speeds around 15 m/s, 33 mph, or 33 knots. It would be uneconomical to design them for operation at the importable higher wind speeds. It is necessary to limit the power output in high wind conditions on all wind Turbines; otherwise a runaway turbine will be overloading its rotors, mechanical power train, as well as its electrical generator leading to catastrophic failure.

It is unavoidable, In order to protect the structural integrity of the wind turbine, to Ignore the energy production potential of these improbable wind gusts and to provide Power controls in modem wind turbines to stop the turbine when these occur.

Wind turbines have to also be oriented perpendicular to the wind stream using wind orientation mechanism or yaw control. In addition their brakes must be applied under unfavorable high wind conditions. Some of these controls are performed mechanically in order wind machines, but in newer machines they are performed hydraulically, and in the most recent designs they are done electrically using stepped up motors.

This is similar to the evolution in aircraft from manual controls to hydraulic controls to fly by wire controls.

Wind energy is currently the fastest-growing source of electricity in the world. Wind power investment worldwide is expected to expand three-fold in the next decade, from about $18 billion in 2006 to $60 billion in 2016. In the U.S., where wind currently only provides about 1% of the nation's electricity, wind has the potential to provide up to 20% of the nation's electricity without major changes to the nation's electricity distribution system. However, there are still many unsolved challenges in expanding wind power.

We will overview the standard controls as well as recently developed advanced controls for variable-speed, horizontal axis wind turbines. For a more general tutorial on wind turbines, It is becoming more common for modern turbines to provide individual pitch actuators at each blade so that the number of control inputs available to the system designer is increased above the traditional generator torque control. In addition, force/moment sensing or accelerometers can be installed at each blade individually as well as on the nacelle and tower. These additional inputs and outputs combine with the fact that the turbine structural