Direct power control of wind-turbine-driven DFIG during transient grid voltage unbalance

In this paper, a direct power control (DPC) of a wind-turbine-driven doubly fed induction generators (DFIGs) under unbalanced network voltage conditions is studied. Variations of the stator output active, reactive and electromagnetic powers are fully deduced in the presence of negative sequence supply voltage. The rotor side converter is controlled on the basis of DPC to eliminate the electromagnetic torque oscillations at double supply frequency under unbalanced stator supply. The rotor voltage references estimation requires only simple calculations without any integral operation. The proposed control scheme removes rotor current regulators and the decomposition processing of positive and negative sequence rotor currents. The performance of the proposed and conventional DPC schemes is compared under the same operating conditions. Simulation results using Matlab/Simulink are carried out for a 1.5MW DFIG wind generation system to show the validity of the proposed scheme during unbalanced voltage supply. Copyright (c) 2013 John Wiley & Sons, Ltd.