Modified Control Technique of DFIG for Power Quality Improvement

Abstract

In this paper, a modified control technique for doubly fed induction generator (DFIG) is presented to improve its power quality by controlling (minimizing) grid current harmonics. The problems of harmonics injection in grid current, especially due to the presence of nonlinear loads, are very crucial. The proposed control technique can transfer the power from grid to DFIG and vice versa and can also control the DC link voltage (Vdc ) against wide variations in wind speeds. The maximum power point tracking (MPPT) is used in rotor side converter (RSC) to control the power flow through the DFIG. The MPPT extracts the maximum electromagnetic torque Tem from wind energy even during wide variations in wind speeds. A comparison of hysteresis current control (HCC) and space vector pulse width modulation (SVPWM) techniques for harmonic mitigation is presented considering all wind speeds. Also, the control technique for RSC and GSC is discussed in detail in this paper. Finally, the performance of the modified control technique to improve DFIG power quality is checked with the help of MATLAB/SIMULINK software considering 2.6 MW DFIG connected to a power grid.