Apparatus for on-line monitoring of transformer winding deformation using leakage inductance identification

Windings of power transformer may suffer short circuit currents or mechanical forces, which lead to different winding displacements such as axial displacements and radial displacements. Measurement of leakage inductance is one of the most effective methods to identify these mechanical displacements. In this paper, an on-line detection system based on WinCE platform for transformer winding deformation is proposed. Based on the equivalent circuit of the transformer for low frequencies, the formula to calculate the leakage inductance on-line is derived. In practice, using the signals gained from the voltage transformers and current transformers, with the help of proper signal filtering method, leakage inductance is calculated in our program. Both the signal processing theory and the algorithm of online leakage inductance estimation are presented. To evaluate the feasibility of the detection system, experiments with and without winding displacements were made using a small transformer and the results of on-line detection were discussed.