Thermal behavior of doubly-fed induction generator wind turbine system during balanced grid fault

Ride-through capabilities of the doubly-fed induction generator (DFIG) during grid fault have been studied a lot. However, the thermal performance of the power device during this transient period is seldom investigated. In this paper, the dynamic model for the DFIG and the influence of the rotor current to the damping time of the stator flux and rotor terminal voltage during the symmetrical grid fault is firstly evaluated. Then, the theoretical analysis for the safety operation area of the power device is given in terms of the various voltage dips and various rotor speeds, in which simulation results are used to verify. Finally, the power loss and the thermal profile are shown at the transient period of the DFIG. It is concluded that, in order to guarantee the same damping time of the stator flux, the serious voltage dip results in the higher power losses as well as the junction temperature fluctuation, and may even damage the rotor converter, if the design is not considered carefully.