Modelling Transfer Function of Power Transformers Using Sweep Frequency Response Analysis

Sweep Frequency response analysis is a widely used condition monitoring technique of power transformers that includes interpreting transfer function in frequency domain. This paper presents a novel approach to model the transfer function numerically in laplace domain. Derivation of transfer function involves complex mathematical calculations as it is a ratio of two high order polynomials resulted by the complex nature of circuitry inside power transformers. An algorithm, based on Levy's and Sanathanan-Koerner method, presented in this paper can be used to derive entire transfer function accurately and more efficiently. Estimated transfer functions using this method can be incorporated in transformer fault diagnosis especially for internal faults caused by winding deformation and core displacement.