Grid Synchronization of Equivalent Wind Farm Equipped with DFIG Model for Transient Stability by Using Nonlinear Integral Backstepping Control

This paper is focused on the study of the grid synchronization of an equivalent wind farm (WF) equipped with doubly fed induction generators (DFIGs) using a nonlinear integral backstepping control (IBSC), in order to improve and accelerate the synchronization of the DFIGs to the electrical grid. In this study, the equivalent model of the WF is obtained by using the semi-aggregation method. This method can be performed by simplifying the mechanical system and by aggregating the electrical system of the wind turbines of the same row. The main contribution of this study is to ensure a good synchronization between the equivalent WF and the electrical grid. This synchronization will be achieved by controlling the rotor currents of the equivalent DFIGs. In this work, the rotor current loops of each equivalent DFIG are controlled by using a nonlinear IBSC algorithm and the proportional-integral (PI) controller. This comparative study between the two controllers is validated by a simulation in Matlab/Simulink environment. The results obtained show that the synchronization between the equivalent WF and the electrical grid is correctly achieved. However, the nonlinear IBSC algorithm has more efficiency and better performance compared to the PI controller.