Integral Backstepping Control Based on High Gain Observer for DFIG-Based Wind Energy Conversion System

Abstract

In this paper, a nonlinear output-feedback controller is designed for the complete wind energy conversion system (WECS), formed by a wind turbine (WT) interfaced to a utility grid (UG) by using a doubly fed induction generator (DFIG) and an AC/DC/AC converter connected with an RL filter. The main objective is to ensure that the output-feedback controller keeps the DFIG speed at the optimum value provided by the MPPT strategy while ensuring control of the stator reactive power and the DC link voltage. To achieve this objective, the integral backstepping approach is used. The DFIG speed and mechanical torque are observed by using a high gain observer. The proposed controller capabilities are verified by numerical simulations using a 2-MW DFIG WT under a variable wind speed profile using MATLAB/SIMULINK/SimPowerSystems environment.