Analysis of ferroresonance in a neutral grounding system with nonlinear core loss

The chaotic behaviour exhibited by a typical ferroresonant circuit in a neutral grounding system is investigated in this paper.In most earlier ferroresonance studies the core loss of the power transformer was neglected or represented by a linear resistance.However,this is not always true.In this paper the core loss of the power transformer is modelled by a third order series in voltage and the magnetization characteristics of the transformer are modelled by an 11th order two-term polynomial.Extensive simulations are carried out to analyse the effect of nonlinear core loss on transformer ferroresonance.A detailed analysis of simulation results demonstrates that,with the nonlinear core loss model used, the onset of chaos appears at a larger source voltage and the transient duration is shorter.