Improved control of rotor- and load-side converters of stand-alone DFIGs under nonlinear loads conditions

Abstract

This paper proposes an improved control of rotor side and load side converters with repetitive control in order to compensate the harmonic components in the stator voltage and current of the doubly-fed induction generator (DFIG) when connected with non-linear loads. The non-linear loads results in distorted stator voltage and current with subsequent power quality degradation and electromagnetic torque pulsations of DFIGs. The distorted stator voltage and current are compensated by the proposed hybrid control scheme with repetitive control (RC) based PI controller (PIRC). The harmonic components of different orders and negative sequence component of the stator voltage can be rejected using a single PIRC while most of the other alternative harmonic compensators require separate controllers for damping these components. The PIRC is applied in rotor side converter (RSC) for the purpose of stator voltage compensation and in line side converter (LSC) for stator current compensation, respectively. The simulation results are given and they show that the PIRC control scheme can eliminate stator voltage and current harmonic of stand-alone DFIG effectively.