Reference current generation schemes for DFIG with unbalanced grid voltage

This paper presents two improved schemes for reference current generation for improved dynamic performance of a Doubly-Fed Induction Generator (DFIG) subjected to unbalanced grid voltage. The focus is on estimating the oscillating power components in addition to the steady state power required from the generator without the need for sequence decomposition. The reference current signals are appropriately modified to minimize the power and torque oscillations. Real and reactive power control is implemented using stator flux oriented vector control. Unlike the previously reported techniques, the proposed schemes enable reduction of oscillations in torque, active and reactive power, and the dc link voltage all in a single target. Numerical simulations are carried out in PSCAD/EMTDC for the laboratory 3-hp DFIG test set up. The results establish that the performance of DFIG can be notably enhanced with the proposed schemes.