Analysis of transient behaviour of power system circuits containing iron cored coils

A general methodology for the computation of transients in a nonlinear circuit containing an iron-cored element is presented. Iron-cored elements are a common nonlinear circuit element in power system circuits. The effect of hysteresis has been taken care of by a simple model based on a piecewise linearisation technique. The eddy current effect is simulated by linear modelling. The method can be used for studying circuit phenomena such as inrush current, ferroresonance and subharmonics. Illustrative examples are presented. B/H (or λ/i) excursions and energy losses, separated into individual components of hysteresis and eddy current losses, occurring in the core during the transient state of the circuit are also computed