Magnetizing Current Harmonics Mitigation Technique for Robust DFIG Operation Under Grid Voltage Distortions

This paper presents a novel method for reference current generation based on magnetizing current for the reliable operation and control of DFIG under harmonically distorted grid voltages. Harmonic components in grid voltage lead to harmonic torque, speed oscillations and mechanical vibrations. Further, the presence of unbalanced and 5
^th
harmonics in grid voltage leads to power pulsations at 100Hz, 200Hz and 300Hz making the DFIG operation unstable. In this study, an improved method using magnetizing current for reference current generation to eliminate the undesirable effects of negative sequence and 5
^th
harmonics on DFIG performance is proposed. Here, the RSC is equipped to mitigate torque and power pulsations through a single target by forcing the pulsating terms of magnetizing currents of negative and 5
^th
harmonic components to zero while maintaining decoupled steady state power flow. The GSC focuses on mitigating the DC link voltage fluctuations while facilitating a unity power factor operation at grid. The new reference currents for RSC and GSC are obtained byadding the negative sequence and 5
^th
harmonic compensating currents to the steady state current references to meet the target. The proposed scheme is validated using PSCAD/EMTDC simulations on a 3 kVA DFIG.