Investigation of Ferroresonance Phenomenon under Different Conditions in Power System

Abstract

Introduction: Ferroresonance is a nonlinear oscillatory phenomenon that occurs in electrical power systems when a capacitance interacts with a nonlinear inductance such as a transformer’s magnetic core. This interaction can produce high overvoltages, distorted waveforms, and potential damage to equipment. Understanding ferroresonance behavior under various conditions is crucial for ensuring power system stability and protection, especially in networks containing single-phase transformers and capacitive components.

Objectives: The main objective of this study is to investigate the ferroresonance phenomenon using a real single-phase transformer under different operating conditions. The work aims to analyze how changes in loading conditions (no-load, resistive load, and R-L load) and variations in series capacitance values influence the occurrence, magnitude, and waveform of ferroresonance overvoltages. The ultimate goal is to identify conditions that minimize or suppress ferroresonance effects in power systems.

Methods: The investigation combines experimental measurements and numerical simulations. A 2 kVA single-phase transformer was modeled, taking into account nonlinear magnetic characteristics and core saturation effects. The simulations were performed using ATPDraw software to model the circuit comprising a voltage source, line impedance, transformer, and varying capacitors. Different scenarios were tested for steady-state and transient regimes, under both unloaded and loaded conditions, to observe the voltage behavior and harmonic distortions induced by ferroresonance.

Results: Simulation results revealed that ferroresonance leads to significant overvoltages and distorted, non-sinusoidal voltage waveforms when the transformer operates in both steady-state and transient conditions. Increasing the series capacitance reduces the amplitude of these overvoltages and improves waveform stability. For loaded transformers, especially with resistive or R-L loads, the phenomenon is less pronounced. When the series capacitance reaches 100 µF, the voltage waveforms become nearly identical and sinusoidal, indicating a stabilized system response.

Conclusions: The study confirms that ferroresonance is highly sensitive to system parameters such as load and capacitance. Small capacitance values intensify overvoltages, whereas larger capacitances mitigate them. Proper selection and control of capacitance can effectively limit ferroresonance and protect electrical equipment. These findings emphasize the importance of considering ferroresonance during the design, modeling, and operation of power transformers and distribution networks.