A proposal for a wind system equipped with a doubly fed induction generator using the Conservative Power Theory for active filtering of harmonics currents

This study describes a strategy that allows the addition of active filtering functionality to a doubly fed induction generator (DFIG) wind power system. The active filtering is performed through an algorithm that uses the mathematical formulation of Conservative Power Theory (CPT) applied into the electric current control loop on grid side converter. The wind power system that uses the CPT to mitigate harmonic currents, allows the improvement of the power quality in electrical power systems where non-linear loads are connected. The active and reactive power control of the DFIG are presented, performed using the stator magnetic flux vector orientation technique. In addition to the detailed description of the back-to-back converter control loops, the controllers design realized by frequency response is presented. The simulation results confirm the possibility of adding the active filtering function in DFIG wind energy systems using the CPT, reducing the THD of the electric current in the grid to less than 5% and improving the power quality in order to comply with the recommendations of the IEEE standardization 519.