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 win turbine system had multiple inputs (pitch angle, field voltage and delay angle), and multiple out-puts (speed and power) and because the requirements conflict, the linear quadratic optimal control method for multivariable systems is used. Two optimal proportional-integral controllers are applied to a detailed 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 is shown that the torsional oscillations in the shaft are well damped.