Using a Nonlinear Controller to Optimize a Variable Speed Wind Power System

Abstract

In this paper an optimal control structure for
variable speed fixed pitch wind turbines is presented. The
frequency separation of the short term and the long term
variations, adopted in the wind modeling, has resulted in a
two loops control structure. The low frequency loop is
based upon a nonlinear (on-off) controller, and the high
frequency loop results from a LQ stochastic problem. The
proposed approach allows to using the advantages of the
on-off control (i.e. robustness), while realizing a trade-off
between the energy conversion maximization and the
control input minimization that determines the mechanical
stress of the drive train. The effectiveness of the whole
structure was tested on an electromechanical wind turbine
simulator.