Ferroresonance suppression in power transformers using chaos theory

► The effect of MOV on ferresonance modes including fundamental, subharmonic and chaos has been investigated. ► The simulation results confirm suppression effect of MOV on ferroresonance. ► Frequency analysis is done for harmonic study in the proposed power system. ► Effect of varying existence system capacitance on occurring ferroresonance has been given. ► Chaos theory is used to analysis the ferroresonance modes in power system. The main goal of this paper is the determination of the effect of the metal oxide varistor (MOV) on various ferroresonance modes including fundamental resonance, subharmonic and chaos mode which are generated in electrical power systems. Chaos theory is used for analyzing this effect. Also, the bifurcation, phase plan diagram and time domain simulation are used for this purpose. The proposed power system contains a no-load or lightly loaded power transformer. The magnetization curve of the transformer core is modeled by a single-value two-term polynomial. The core loss is modeled based on the flux of the transformer. The MOV modeled as a nonlinear voltage dependent resistance. The suppression effect of MOV on chaotic ferroresonance in power transformer is studied in this paper. The simulation results confirm that connecting the MOV to the transformer has a considerable suppression effect on ferroresonance phenomena.