A novel direct power control method for doubly fed induction generators

Abstract

This paper deals with direct control of active and reactive powers in a doubly fed induction generator (DFIG). The stator flux space vector is firstly estimated in the stationary reference frame and then transformed to the rotor reference frame. The suitable rotor voltage space vector is calculated using a switching table based on the errors in stator active/reactive powers. The ordinary direct power control (DPC) method uses six active voltage vectors together with two zero vectors. It suffers from variable switching frequency. The proposed method uses the space vector modulation scheme to supply the rotor with optimal voltage vectors in order to minimize the power errors. Simulations are performed to compare the proposed DPC method with the ordinary method, which show the superiority of the proposed method in terms of lower power ripple and Total Harmonic Distortion (THD).