FEM Simulation and Analysis on Stator Winding Inter-turn Fault in DFIG

With the development of renewable energy technology, Doubly-Fed Induction Generators (DFIG) are widely used on wind farms. Faults of machines have a direct influence on the safety and effectiveness of the power grid. In order to explore failure mechanism, it is of great importance to study the DFIG fault simulation models and features. In this paper, a Finite Element Method (FEM) simulation model of stator winding inter-turn fault in DFIG is presented by the software of ANSYS Maxwell. Different stator inter-turn short circuit fault conditions are achieved by changing the stator winding connection and the values of end leakage-inductance and resistance. Under normal condition, different branches' currents are the same in each phase and different phase currents are balanced. So the Total Harmonic Distortions (THD) of threephase stator currents are low and phase differences of stator currents are all about 120 degrees. Additionally, Park's vector trajectory is a circle and its eccentricity is approximately zero. However, as the fault degree enlarges, both the current of faulty-branch and the eccentricity of Park's vector trajectory increase. The phase differences related to faulty-phase and THD of faulty-phase become larger. Therefore, THD, phase differences and the eccentricity can be regarded as three fault features to diagnose fault phase and fault degree.