Recognition of power transformer winding movement and deformation using FRA

Purpose - The purpose of this paper is to present a frequency domain technique for the recognition and location of winding movements and mechanical deformations in power transformers. Both, axial and radial coil movements, as well as changes in clamp pressure will be studied. Design/methodology/approach - The developed algorithm is based on using a distributed s-domain parameter equivalent network, which is cascaded with other sections to constitute a generalized model. The frequency domain transfer admittance is used as the main criterion to recognize, identify and locate the winding movement and deformation. Findings - In order to reduce the number of failures due to winding movements and deformations, it is suggested to measure and store the transfer admittance over frequency range 0-10MHz region at normal operation as saved data for comparison with the corresponding data during failure. With the proposed technique, the type and the location of eventual displacement, as well as the number discs involved can be identified. Research limitations/implications - Although the simulation was based on real experimental data adopted from the literature, the algorithm should be tested for real transformers. Several checks have been conducted in order to validate the mathematical model. Originality/value - A relatively simple mathematical model has been presented. It can be used for any transfonner, to check the integrity of the winding in order to meet certain degree of equipment safety and reliability.