DFIG performance improvement in grid connected mode by using fractional order [PI] controller

This article has focused on designing and applying the fractional order [PI] (FO[PI]) controllers in the rotor side converter (RSC) of a doubly-fed induction generator (DFIG) wind turbine in the wind farm connected to a weak grid. To design the controllers, an analytical approach is developed to ensure the frequency domain specifications. The proposed fractional order controllers are simultaneously applied in the internal and external control loops of the RSC to improve DFIG active power, rotor speed and rotor current profiles by occurring various balanced and unbalanced transient faults. Different simulation results are obtained to verify the efficacy of the proposed method at both middle and high mean wind speeds. Meanwhile, the uncertainty in the grid parameters including the short circuit capacity (SCC) and X/R ratio is surveyed by reducing these parameters to show the superior performance of FO[PI] controllers in comparison with PI ones.