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Ferroresonance occurrence is a source of damage, causing overvoltage on voltage transformer (VT) and isolators of the grid equipment. Some solutions are available to protect VTs from the ferroresonance overvoltage. However, they just act after the ferroresonance occurrence. In this letter, to prevent the occurrence of ferroresonance, a dc reactor-based protection device is introduced. Analytical studies and simulations by MATLAB/Simulink and Maxwell ANSYS demonstrate the capability of the proposed protection device as a VT ferroresonance inhibitor. Experimental results from a scaled-down laboratory prototype are also provided to verify the proposed solution. [ABSTRACT FROM AUTHOR]

This paper proposes a smart dual function series resonance ferroresonance overvoltage and fault current limiter (SRFFCL) for distribution networks. The studied network has potential transformers (PTs) with a typically low thermal capacity and high accuracy. The PT core losses are assumed to be constant during ferroresonance oscillation. The MATLAB software is used for simulation of the novel SRFFCL in distribution network, to study the PT ferroresonance overvoltage and fault current. Also, experimental results are obtained using a laboratory prototype. Both the simulation and experimental results, which are in good agreement with each other, show that the suggested SRFFCL can not only control the fault current but also adequately decrease the ferroresonance oscillation of the PT. [ABSTRACT FROM AUTHOR]

This study presents a novel DC reactor‐based ferroresonance and fault current limiter (DRFFCL) for stabilising ferroresonance oscillations of potential transformer (PT) in 33 kV distribution network and decreasing the amplitude of the fault current to an acceptable level. At first, the ferroresonance overvoltage is introduced and various types of overvoltage in the PT are studied. Then, the effects of the suggested DRFFCL on these oscillations are investigated. It is shown that the proposed DRFFCL not only can control the ferroresonance oscillations, but also can decrease the fault current amplitude in the case of short‐circuit faults occurrence. The DRFFCL performance is simulated using MATLAB software and a scaled‐down laboratory prototype is implemented and tested for the simulation results validation. The measured results are in agreement with the simulation results and clearly show the ability of the DRFFCL for controlling both the ferroresonance overvoltage and fault current. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

In this article, a simple case of ferroresonance in a three-phase transformer is used to study the effect of a metal oxide surge arrester on the control of chaotic ferroresonance and duration of chaotic transient in a power transformer including non-linear core losses. The time-domain simulations are derived using MATLAB (The MathWorks, Natick, Massachusetts, USA) for a three-phase 50-MVA, 635.1-kV power transformers while one of its phases is opened. The magnetization characteristic of the power transformer is modeled by a single-value two-term polynomial. The non-linear core losses are modeled by a third-order power series in terms of voltage, and the core losses non-linearities are considered as well. The simulation results show that connecting the metal oxide surge arrester to the transformer exhibits a great suppressing effect on occurred ferroresonance over-voltage. [ABSTRACT FROM PUBLISHER]

Ferroresonance is a non-conventional electrical phenomenon which may cause overvoltages in the electrical power system endangers the system reliability. This paper studies the effect of circuit breaker shunt resistance, Metal Oxide Surge Arrester (MOSA) and neutral earth resistance on controlling chaotic ferroresonance in a potential transformer while transformer core losses is modeled as a nonlinear resistance which hysteresis and eddy current losses are included. It is expected that neutral earth resistance can control ferroresonance better than MOSA and circuit breaker air gap resistance. For confirmation this aspect, simulation has been done on a one phase potential transformer rated 100VA, 275kV. Simulation results show that considering shunt resistance on the circuit breaker and MOSA in parallel to the transformer, exhibits a great mitigating effect on ferroresonance oscillations, but these resistances cannot control these phenomena for wide variation of the power system parameters. By applying neutral earth resistance to the system grounding, ferroresonance is controlled and its amplitude has been damped for all parameters values. [ABSTRACT FROM AUTHOR]

Ferroresonance or nonlinear resonance is a complex electrical phenomenon, which may cause over voltages and over currents in the electrical power system which endangers the system reliability and continuous safe operating. The ability to predict or confirm ferroresonance depends primarily on the accuracy of the transformer model used by the computer simulation. An overview of available literature and contributors to this area is provided. This paper studies the effect of circuit breaker shunt resistance on the controlling chaotic ferroresonance in a voltage transformer while the core losses of the voltage transformer core are highly nonlinear. It is expected that this resistance generally can cause ferroresonance 'dropout'. For confirmation this aspect Simulation has been done on a one phase voltage transformer rated 100VA, 275kV. The magnetization characteristic of the transformer is modeled by a single-value two-term polynomial with q=7. The simulation results reveal that considering the shunt resistance on the circuit breaker in the case of nonlinear core losses, exhibits a great mitigating effect on ferroresonance over voltages. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance over voltages has been obtained and presented. [ABSTRACT FROM AUTHOR]