Online power transformer diagnostics using multiple modes of microwave radiation to reconstruct winding conductor locations

Abstract

A novel approach to diagnostics of transformer winding deformations, caused by mechanical forces from short-circuit currents, is presented. We employ a simple model of a transformer as a two-dimensional parallel plate waveguide. The upper plate represents the transformer tank wall and the lower plate represents the iron core which carries the magnetic flux. Between the two plates, we model the transformer winding by a set of parallel conductors. We utilize commercial simulation software to simulate the generation and measurement of microwave radiation at both ends of the winding structure. The radiation interacts with the metallic structures in the model waveguide. The measured responses from the model waveguide are expected to be sensitive to mechanical deformations of the transformer winding. We use conventional waveguide theory to solve the direct propagation problem, and an optimization method to solve the inverse problem. In particular, we determine the locations of winding segments, and obtain a good agreement between reconstructed and true conductor positions.