Anotace:
Ferroresonance is an oscillation in a nonlinear circuit containing transformers at lightly load or no-load coupled with capacitor. The non-linear behaviour of the core material of the transformer at no-load is represented by a nonlinear equation. The capacitive effects of the power network are treated as a capacitor in series with the transformer equivalent circuit. As the system contains a nonlinear equation, it was difficult to analyse the model using the linear method. The finite Element Method is used here for the simulations of ferroresonance. The Finite Element Method allows a field solution to be obtained, even with time-varying fields with non-homogeneous or non-linear fields. This method helps to find out the changes that occur in the magnetic structure of the core under ferroresonance. Supply voltage is taken as the variable parameter. Capacitor and transformer voltages along with the phase plane are analysed before and after the occurrence of ferroresonance over-voltage. Distribution and change in the magnetic flux during the triggering of ferroresonance are also examined.