Modeling and investigation of small-signal stability of DFIG-based wind energy system using linear quadratic integral controller

Abstract

This work demonstrates the effectiveness of the linear quadratic integral (LQI) controller over the linear quadratic regulator (LQR) controller for the small-signal stability of the doubly fed induction generator (DFIG)-based wind energy system. To design the proposed controller, the studied system has been described by the state-space linearization methodology. The eigenvalues and time response analysis method are used to examine the small-signal stability as well as the dynamic responses of the system. This study also considers to cancel the steady-state offset values in the powers flow through the DFIG and the generator-angular speed for complete disturbance rejection during the mechanical torque variations which are caused by the change in the wind speed. All the simulation results are performed in the MATLAB/SIMULINK and conclude that the proposed controller is much better than the classical LQR controller in terms of damping, eigenvalues, peak values and steady-state errors in the output variables.