Feature Analysis of Oscillating Wave Signal for Axial Displacement in Autotransformer

A new testing method (oscillating wave method) has been proposed as a solution to the problem of short maintenance time in traction power supply system, which could complete tests of winding and insulation via one connection and improve the maintenance efficiency of the transformer. Through the method being proved highly sensitive to winding faults, the variation under different winding states, however, remains unclear. This paper aims to analyze oscillating wave signatures in the occurrence of axial displacement (AD). Firstly, the modeling method will be proposed that can simulate oscillating wave signatures in different winding states. Then, the time-domain feature and the new proposed frequency-domain feature are applied to analyze the fault extent and location of AD fault. The results show that this model accurately simulates oscillating wave signatures. Moreover, the time-domain feature (Euclidean distance-ED) is closely related to fault extent. The combined use of the time-domain feature (ED) and frequency-domain feature (W-Energy entropy in Z-Score) is effective in the identification of fault location. These features, therefore, can provide the reference for winding state evaluation.