Robust Controller Design for Speed Regulation of a Wind Turbine using 16-Plant Theorem Approach

Large scale wind turbines are subjected to fatigue, aerodynamics, structural flexibility and wind turbulence which lead to uncertain behavior of the wind turbine. The uncertainties are due to differences between the mathematical model and the actual dynamics of the system in operation and the worn and torn effects. These elements are combinations of mass, stiffness, damping factors and moments of inertia of the rotor and generator. The uncertainties or perturbations in the wind turbine are indicated by variations between ±25% of the nominal values of the elements of the system matrix. These uncertainties in the wind turbine are dealt with the proposed robustly stabilizing controller in this paper. The stable (Kp, Ki) regions of a Proportional-Integral (PI) controller are chosen by the Kharitonov’s theorem based 16-plant model. It can be shown that a simple PI controller can become robust by the correct selection of its parameters. The furnished results validate the above statement.