Performance study of grid-connected Doubly-Fed Induction Generator controlled by an optimal controller under unbalanced condition

Abstract

Effective addressing of the controller of a converter used in the doubly-fed induction generator (DFIG) under unbalanced grid voltage conditions is imperative. To reduce the effects of negative sequence voltages such as oscillatory components in the torque, negative sequence components in the stator and rotor current are required to add in the main control algorithm. In this study, an optimal control algorithm has been proposed for the achievement of various functional characteristics such as stator and rotor current, torque, active and reactive power of the DIFG. In addition, different scenarios for the designing of an optimal controller, an additional function is implemented to reduce the negative sequence has been proposed. The simulation was carried out using PLECS software. Detailed analysis was made to study the performance of the system. Simulation results illustrated the proposed optimal control algorithm improving the entire operational characteristic simultaneously. Finally, comparison has been done to study the performance of the proposed method with three other controllers. The comparison result showed the proposed optimal controller limiting the variations in the amplitude of negative sequence components of rotor current and negative sequence components of stator current to 1% and 1.4% respectively.