Modelling of DFIG based Wind Turbine to Identify Stator Interturn Short Circuit Fault using Frequency Domain Analysis

Interturn short circuit (ITSC) fault is a common electrical fault that occurs mostly as a result of the continuous aging of the machine's winding insulations, and it can have catastrophic repercussions if not diagnosed early. The proposed work demonstrates the identification of stator winding ITSC fault of a doubly fed induction generator (DFIG) in a grid-connected wind turbine system. The findings indicate that an ITSC failure disturbs DFIG currents, influencing input voltages and output currents of stator-side converter. The simulation model consists of DFIG WT with ratings of 1 MVA, 400V, and 50Hz. At time t = 1.5 seconds, a short circuit occurs in the stator winding in phase 'a', causing increase in the current, Isa. The current signal from the stator winding is analysed using the power spectrum approach in the frequency domain. Instability in the grid connection is caused by variations in the active and reactive power supplied to the grid due to fault. Thermal impact on winding insulation and adjacent turns occurs as a result of fault current circulating in damaged turns. As the ITSC fault spreads quickly, the insulation of the other two phases may be compromised as well. As a result, it is critical to recognize such flaws early on so that corrective actions can be taken to eliminate them.