Adaptive interval observer design with application to wind energy converters

Estimation of state variables is a very important instrument for control system design. When the system has a nonlinear behavior that can be represented by a family of linear models whose parameters are arranged as interval vectors, it is useful to reckon with a different observer that is able to manage such models. In this contribution, the design of an adaptive observer for interval models is presented. The observer is used for the estimation of the state variables of a very large wind turbine, which cannot be assumed rigid and therefore the linear model changes with wind speed. The observer is also extended to estimate the effective wind speed. The interval modelling process is also included. Simulation of a high-definition model combined with the observer based on a middle-definition model yields satisfactory results. Thus, the observer provides useful values of state variables that can be used for vibration control.