Realization of transformer winding network from sweep frequency response data

Sweep Frequency Response analysis (SFRA) is a widely used technique for condition assessment of power transformers and reactors. With SFRA, it is possible to analyze the integrity of transformer without prior dismantling. Changes in geometric configuration change the impedance of network which in turn changes the transfer function. Changes in transfer function will reveal a wide range of failure modes. SFRA allows the detection of changes in transfer function of individual windings within transformers and reactors and indicate movement or distortion in core and windings of the transformer. The RLC network can be identified by its frequency dependent transfer function. In order to create a framework to facilitate assisted interpretation algorithms, SFRA curves are parameterized. The simplest and most useful mechanism is the reduction of the curves to pole-zero representation. SFRA traces are characterized by having many undulations and extending over a wide dynamic range on both axes. This can make accurate pole-zero representation a challenge. In this paper an attempt has been made to realize the electrical network from the SFRA response data of a high voltage reactor.