Hysteresis modeling in the MATLAB/Power System Blockset Original Research Article

blocks in the Power System Blockset (PSB), a MATLAB/Simulink®-based simulation tool. This model will be available in version 3.0 of the PSB (also called SimPowerSystems) and offered as an alternative to the actual core saturation characteristic. The effect of hysteresis and eddy losses are of significance in the studies of: sub harmonic; residual flux effects on the transformer inrush currents; ferroresonance phenomena; harmonics generated by half-cycle saturation. The static model of hysteresis defines the relation between the flux Φ and the magnetization current (i.e. the current through the nonlinear inductance in the model) that is equal to the total excitation current measured in dc (when the eddy current losses are not present). It is useful under transient conditions and can represent minor loops. The principal points are: in transient conditions an oscillating current will produce minor asymmetrical loops; inside a minor loop the excitation curve depends only on the last two reversal points, and each curve tend to return to the reversal point previous to the last. A hysteresis design tool consisting of graphical user interface (GUI) allows precise adjustment to any major loop or saturation characteristic. An animation option of the GUI permits an open loop simulation so to visualize the operating point displacement within the major loop and the formation of the minor loops. Finally, an example case is described to illustrate remanent flux and inrush current at transformer energization.