Nonlinear control strategy for wind turbine based on DFIG to enhance the LVRT capability

Abstract

Under voltage dip conditions, the induced rotor over-currents of the doubly fed induction generators (DFIG) may greatly destroy the converter switches. In this paper, a nonlinear control based on integral backstepping control (IBC) strategy is presented to enhance the Low voltage ride-through (LVRT) of DFIG. The goal of the proposed control strategy applied to rotor side converter (RSC) and grid side converter (GSC) is the enhancement of transient performance of DFIG and limitation of DC-link overvoltage. In addition, to fulfill LVRT requirements, DFIG powers control strategy is developed to maintain the voltage at point of common coupling (PCC) within standard bound, specifically in voltage dip disturbance resulting from unbalanced grid faults. The simulation results are achieved by using Matlab/Simulink to prove the effectiveness of the proposed control strategy.