Analysis on Transient EMF Variation Characteristic of Doubly Fed Induction Generator After Crowbar Protection Activated

In recent years the equivalent transient model of doubly fed induction generator(DFIG) becomes one of the research foci related to protective relayings. For the operating condition of DFIG in which the crowbar circuit is put into use, on the basis of analyzing variation process of rotor flux linkage the variation characteristic of DFIG's transient EMF is quantitatively researched. It is pointed out that due to the slip there is alternating component with slip frequency in the transient EMF; the attenuation speed of the decaying component in the transient EMF is accelerated by putting the crowbar resistance into use, so it make the transient EMF of DFIG appearing the feature of rapid decay and it is different from the slow decay feature of transient EMF in traditional synchronous generators. The correctness of the theoretical analysis is validated by simulation. Result of this research is available for reference to the follow-up establishment of equivalent transient model for DFIG and the research on protection strategy for wind farms.