Comparison of internal voltage vectors of DFIG-based wind turbine generator and synchronous generator during asymmetrical fault

Fault signatures of doubly fed induction generator (DFIG) based wind turbine generators (WTGs) are different and more complex than that of synchronous generators (SGs). This paper proposes a new approach to elaborate the formation of the fault signatures of DFIG-based WTGs under asymmetrical faults and various fault ride through control. The proposed internal voltage vectors and equivalent circuit enable reorganizing the control schemes, electric and magnetic circuits of DFIG in terms of transient, positive- and negative-sequence components. This way, the characteristics of DFIG-based WTGs and SGs can be compared in a similar frame through their internal voltage vectors. The differences and similarities are summarized in support of protection and control designs.