Analyzing Ferroresonance Phenomena in Power Transformers Including Zinc Oxide Arrester and Neutral Resistance Effect

Abstract

This paper studies the effect of zinc oxide arrester (ZnO) and neutral earth resistance on controlling nonconventional oscillations of the unloaded power transformer. At first, ferroresonance overvoltage in the power system including ZnO is investigated. It is shown this nonlinear resistance can limit the ferroresonance oscillations but it cannot successfully control these phenomena. Because of the temperature dissipation of ZnO, it can withstand against overvoltage in a short period and after that ferroresonance causes ZnO failure. By applying neutral earth resistance to the system configuration, mitigating ferroresonance has been increased and chaotic overvoltage has been changed to the smoother behavior such as fundamental resonance and periodic oscillation. The simulation results show that connecting the neutral resistance exhibits a great mitigating effect on nonlinear overvoltage.

Novel Circuit Breaker Modeling in 275kV Substation

“…with eld test results. The inuence of supply, circuit and magnetic material parameters on the occurance of the fundamental ferroresonance mode in a series inductance-capacitance-resistance (LCR) circuit with a nonlinear inductor has been discussed in [18] and [19]. The eect of the circuit breaker shunt resistance on the chaotic ferroresonance in voltage transformers has been studied in [20].…”

Resistive Ferroresonance Limiter for Potential Transformers

“…The ferroresonance is typically initiated by saturable magnetizing inductance of a transformer and a capacitive distribution cable or transmission line connected to the transformer. In most practical situations, ferroresonance results in dominated currents, but in some operating "mode", may cause significant high value distorted winding voltage waveform, which is typically referred to as ferroresonance [1]. Although occurrences of the "resonance" involves a capacitance and an inductance, there is no definite resonant frequency.…”

“…In this phenomenon, more than one response is possible for the same set of parameters, and drifts or transients may cause the response to jump from one steadystate response to another one. Its occurrence is more likely to happen in the absence of adequate damping [1]. Researches on ferroresonance in transformers have been conducted for more than 80 years.…”