Fractional Derivative Approach in Modeling of a Nonlinear Coil for Ferroresonance Analyses

The article presents the results of the computations performed for a ferroresonant circuit. Two models for the coil with a ferromagnetic core were used in the simulations. The conventional parallel model and one applying a fractional derivative. Calculations of applied model parameters were obtained through estimations based on measured and recorded steady-state waveforms of currents and voltages of the particular circuit components. The experiment was conducted over a wide range of levels of the supply voltage. During the experiment, the coil worked in the saturation conditions of the magnetic core, but intentionally without reaching the point where ferroresonance occurs. Measurements and recordings were made using the digital interference recorder RZ-1 developed by Kared (Gdansk). Parameter estimations and simulations were performed in Matlab.