Experimental research and feature extraction on stator inter-turn short circuit fault in DFIG

Abstract

Nowadays the Doubly-Fed Induction Generator (DFIG) is equipped for many large wind farms. Its faults have a deep influence on the safety and effectiveness of the machine and huge cost is required for maintenance. Investigations have revealed that stator inter-turn short circuit fault may lead to more serious problems. More researches are to focus attention on fault detection and preventive maintenance strategies for industrial plant. In this paper, an experimental platform is developed, which can conduct different stator winding inter-turn faults, and some fault feature parameters are extracted and analyzed. Stator line currents are used for calculating RMS, phase difference, negative-sequence, and the Park's vector trajectory's eccentricity as feature parameters. Stator line currents are balanced under normal condition, so the negative sequence of stator currents is almost zero, and their phase differences are about 120°. The park's vector trajectory is a circle under healthy condition, and its eccentricity is near to zero. When stator short circuit fault occurs, the negative sequence and the Park's vector trajectory's eccentricity are increasing as fault degree enlarges, and also the phase differences related to fault phase increase while the other reduces. Finally, the experimental setup simulated the expected stator inter-turn short circuit fault successfully, and the extracted feature parameters will contribute to fault diagnosis of DFIG.