Dynamic thermal analysis of DFIG rotor-side converter 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 DFIG performance in terms of the stator flux evolution and the rotor voltage during the balanced grid fault is firstly addressed. By using the traditional demagnetizing control, the damping of the stator flux and the safety operation area are theoretically evaluated with various amounts of demagnetizing current. It is observed that the higher demagnetizing current leads to faster stator flux damping and lower induced rotor voltage, but it brings higher loss as well as the thermal cycling of the power device. Based on the simulation of the stator flux evolution and the thermal behavior of each power semiconductor, it is concluded that there is a trade-off in selection of the demagnetizing current coefficient, and it should be jointly decided by the suitable transient period and reliable operation of the power device.