A Procedure for the Development of Control-Oriented Linear Models for Horizontal-Axis Large Wind Turbines

In this work we describe a methodology to construct control-oriented, multi-input, multi-output linear models representing the dynamics of variable-speed, pitch-controlled horizontal-axis wind turbines (HAWT). The turbine is treated as an interconnection of mechanical elements with distributed mass, damping, and stiffness characteristics. The behavior of the structural components of the turbine is approximated as that of their dominant modes and the wind-blade aerodynamic interaction is modeled using the Blade Element Momentum (BEM) theory. The modeling procedure explicitly exploits the horizontal-axis configuration and constraints imposed thereof. The models developed using the outlined procedure are parametrized based on a handful of parameters that are often used to specify mass/stiffness distributions and geometry. The predictions of the linear models so constructed are validated against that of an established nonlinear model. The use of the modeling procedure in addressing problems of immediate interest to the wind turbine industry is presented.