The rotor-circuit (RC) of the doubly fed induction generator-based wind turbine (DFIG- WT) consists of various equipment in which faulty conditions must be immediately identified, because this faulty status leads to the loss-of-excitation (LOE) phenomenon and may cause some serious damages. In this regard, this paper develops a novel solution to protect the DFIG-WT during such a condition. For this purpose, a comprehensive inves- tigation on behavior of the DFIG-WT during the conditions of the RC failures has been carried out. The results show that, the output active power of the machine (Pdfig) can be considered as a suitable initial indicator for detecting the RC failures. However, to reliable detection of the partial-LOE (PLOE), complete-LOE (CLOE) and discrimination from the other power system disturbance (PSD), a directional over-current (DOC) and an under voltage (UV) relays are suggested to be installed in the RC, at both ends of the back-to- back converters. Consequently, by detecting the Pdfig decrement, the provided DOC and UV relays in the RC will be triggered to classify the occurred events. The outlined pro- tection scheme is exhaustively investigated on a typical power system which the obtained simulation results show the high reliability in discriminating the RC failures and PSD events with an acceptable detection time.
