Optimal multivariable control of a wind turbine with variable speed

The control system design for a 310 kW horizontal axis wind energy conversion system with a synchronous generator and DC link is investigated. Because the wind turbine system has multiple inputs (pitch angle, field vollage alld delay angle), and multiple outputs, (speed and power), and because the requirements conflict, the linear quadratic optimal control method/or mullivariable systems is used. Two optimal proportional-integral controllers are applied to a delailed non-linear dynamic model. With simulations it is shown that, even when a large gust occurs, the speed and power fluctuations are very small. With an eigenvalue analysis it is shown that the torsional oscillations in the shaft are well damped.