Ferroresonant Configurations in Power Systems

Abstract

Over the last decades, power disturbances have become an important factor on the increase throughout electrical networks, which can exert an important influence over power quality ratios. Amongst them, it is worth mentioning ferroresonance, which is a special case of resonance involving non-linear inductances that mainly affects the functionality of transformers. Its effects are characterized by high sustained overvoltages and overcurrents with maintained levels of current and voltage waveform distortion, producing extremely dangerous consequences. The first step against ferroresonance is always to prevent it from appearing, so it is important to identify those electrical configurations prone to the appearance of the phenomenon. Therefore, this paper analyzes different ferroresonant configurations that may take place in power systems, highlighting some of the most relevant aspects of each configuration.

Analysis and mitigation of ferroresonant oscillations in power system

“…An overview of possibly dangerous network configurations can be found in e.g. [3], [4], [5]. Following conditions must be met so that ferroresonance appears in an electrical circuit [4]:…”

“…It results in a degradation of insulating materials, overheating, damage to a device or even a complete destruction. Thus, when ferroresonance appears in electrical power system, it is necessary to mitigate it and bring the electrical system to normal state [1], [2], [3], [4], [5].…”

Verification tests of a novel ferroresonance detection technique

“…Nowadays, the most common measure against ferroresonance is the permanent inclusion of a damping circuit (ferroresonance suppression circuit) in the secondary winding of the transformer. The final design of this ferrorresonance suppression circuit depends on the transformer type and the electric configuration of the power system [7][8]. Figure 1 shows the typical elements included in the design of a ferroresonance suppression circuit [9].…”

Power Oscillation Due to Ferroresonance and Subsynchronous Resonance

“…Severity of ferroresonance is classified as four categories like fundamental, harmonic, quasi-periodic, and chaotic [2]. Ref [3] explains Conventional configurations which lead in ferroresonance like; voltage transformer (VT) energized through the grading capacitance of open circuit breakers or VT connected to an ungrounded neutral system, circuit breaker failure during opening or closing operation, and power transformer supplied through a long transmission line cable with low short-circuit power [3]. Several methods have been presented to analyze ferroresonance in time and frequency domain.…”