Numerical Modeling, Electrical Characteristics Analysis and Experimental Validation of Severe Inter-Turn Short Circuit Fault Conditions on Stator Winding in DFIG of Wind Turbines

Inter-turn short circuit fault (ITSCF) can be a great threat for the safety and effectiveness of the generator. In this paper, a simulation model with the experimental platform is established to diagnose the ITSCF in stator windings. A simulation model based on the Finite Element Method (FEM) is designed in ANSYS. Stator current is used for calculating the Root-Mean-Square (RMS) value, phase difference, symmetrical components, Park's vector trajectory's and Total Harmonic Distortion (THD). It was found that when ITSCF happened, three phase currents in stator is no longer symmetrical. The ratio of negative to positive sequence of current raises from 0.40 to 14.18 in simulation and 0.52 to 19.89 in the experiment from normal condition to 7 turns shorted. The same trend was seen in Park's vector trajectory analysis where the eccentricity raises from 0.03 to 0.65 in simulation and 0.14 to 0.75 in the experiment. Phase difference of the three phases is at 120° degree deviation as the ITSCF occurs in stator winding. THD also increased with the increase in the fault level. The results show a good consistency of simulation with experimental results. It was found that the analysis performed in this research are major indications for serious fault in DFIG.