Transient behavior analysis of Doubly-fed induction generator under unbalanced voltage dips and testing validation

Normally, it´s more difficult to realize Low Voltage Ride through (LVRT) for Doubly-fed induction generator (DFIG) under unbalanced voltage dips than in balanced voltage dips. Unbalanced dips are more harmful to the Doubly-fed induction generator (DFIG) than balanced dips, because they induce higher voltages in the rotor. Besides, the influence of unbalanced grid voltage dips to DFIG is studied together with the transient behavior of DFIG. A theoretical analysis is given to the reasons of the over current occurring during an unbalanced grid voltage dips in this paper. Field testing results with mobile LVRT testing container are also presented to support the analysis.