Non Linear Control of a Wind Energy System

Abstract

This work is located in wind turbine - DFIG (doubly fed induction generator) speed control field. The main objective is to maximizing the wind energy extraction. Many works presented optimal wind-turbine speed control strategies. In this work, a maximum power point tracking (MPPT) control strategy devoid of any mechanical sensor is developed. Two objectives are fixed to the controller (i) tracking the maximum available wind power; (ii) regulating the DFIG reactive power. The access of mechanical values being difficult from measurement, are estimated using a nonlinear observer based on the state space model representing the whole DFIG-wind turbine. Moreover, using the estimated mechanical variables, a nonlinear control law is developed with the sliding mode technical to achieve the global stability of the association between the machine, the observer and the controller. The performances of the proposed regulator are analyzed using tools from the Lyapunov stability. A wide variation of the wind speed is applied in simulation to validate the theoretical results.