Analysis of Ferroresonance in a Power Transformer with Multiple Nonlinearities

Abstract

This paper investigates the chaotic behavior exhibited by a typical ferroresonant circuit under two-phase open condition. The circuit includes multiple nonlinear elements that accounts for transformer core nonlinearities and arrester. In most of the ferroresonance studies the core loss of the transformer is neglected or modeled as linear resistor [1]. The basic model of the system under investigation and solution of the differential equations describing the model are corroborated against MicroTran [2]. Choice of state variables and formulation of state equations are accomplished through a topological approach [3]. Extensive simulations have been carried out to analyze the sensitivity of the state variables with respect to degree of core saturation, amplitude of the Thevenin voltage source and the presence of arrester. Time response plots, phase plots, Poincaré maps and conventional bifurcation diagrams are used to analyze the chaotic behavior. The results reveal that the nonlinear model of core loss has a significant effect on the onset of chaos. The simultaneous presence of arrester and nonlinear model of core loss effectively eliminates the chaotic region for lower value of transformer saturation exponent.