Nonlinear Core Losses Research Articles

Characteristic Analysis of Transformer Loss with Subsynchronous Components by Field-Circuit Coupled Time Periodic FEM

A field-circuit coupled finite element calculation model embedded loss separation theory is proposed, which can effectively deal with the nonlinear core loss of transformer caused by subsynchronous frequency components injection. In order to deal with the increased time period due to the subsynchronous frequency components, and the problem of excessive loss current and too small parallel resistance due to zero-crossing point of voltage, the Parareal algorithm is introduced to solve the model. The algorithm is verified by the experiments of the physical transformer under the conditions of rated fundamental voltage and with subsynchronous components, respectively.

The Influence of Electrical Sheet on the Core Losses at No-Load and Full-Load of Small Power Induction Motors

This paper presents the core losses and performance characteristics of a small power induction motor with the core made from different electrical sheets, supplied from mains or PWM frequency inverter at 50, 100, and 200 Hz. Field-circuit and analytical methods are used for loss calculations, taking into account the nonlinear phenomena and additional core losses. In the calculations, the characteristics of mechanical losses measured against the speed for the motors and different electrical sheets magnetization, for frequencies up to 2000 Hz, as well as losses density characteristics against the flux density were used. The results show a significant increase in core losses concomitant with the motor load increase. In addition, analytical methods were used to calculate the performance characteristics versus load power. Calculated results were verified by measurements.

Effect of metal oxide arrester on the chaotic oscillations in the voltage transformer with nonlinear core loss model using chaos theory

In this paper, controlling chaos when chaotic ferroresonant oscillations occur in a voltage transformer with nonlinear core loss model is performed. The effect of a parallel metal oxide surge arrester on the ferroresonance oscillations of voltage transformers is studied. The metal oxide arrester (MOA) is found to be effective in reducing ferroresonance chaotic oscillations. Also the multiple scales method is used to analyze the chaotic behavior and different types of fixed points in ferroresonance of voltage transformers considering core loss. This phenomenon has nonlinear chaotic dynamics and includes sub-harmonic, quasi-periodic, and also chaotic oscillations. In this paper, the chaotic behavior and various ferroresonant oscillation modes of the voltage transformer is studied. This phenomenon consists of different types of bifurcations such as period doubling bifurcation (PDB), saddle node bifurcation (SNB), Hopf bifurcation (HB), and chaos. The dynamic analysis of ferroresonant circuit is based on bifurcation theory. The bifurcation and phase plane diagrams are illustrated using a continuous method and linear and nonlinear models of core loss. To analyze ferroresonance phenomenon, the Lyapunov exponents are calculated via the multiple scales method to obtain Feigenbaum numbers. The bifurcation diagrams illustrate the variation of the control parameter. Therefore, the chaos is created and increased in the system.

Novel Circuit Breaker Modeling in 275kV Substation

Ferroresonance an electrical phenomenon may cause overvoltages in the electrical power system. In this paper, an overview of available papers is provided, at rst ferroresonance is introduced and then various type of ferroresonance in a voltage transformer (VT) is simulated. Then eect of new model of circuit breaker (CB) on damping ferroresonance oscillation is examined. Finally eect of earth resistance on the stabilizing these oscillations in the case of nonlinear core loss has been studied. Core loss is modelled by third order power series in terms of voltage and includes nonlinearities in core loss. For conrmation, the simulation is done on a one phase voltage transformer rated 100VA, 275kV. The simulation results reveal that novel modeling of circuit breaker exhibits great controlling eect on ferrores- onance overvoltages.

Chaotic oscillations control in the voltage transformer including nonlinear core loss model by a nonlinear robust adaptive controller

In this paper, control of chaos is done in presence of ferroresonant oscillations in a voltage transformer with nonlinear model of core losses. In order to control the chaotic oscillations, nonlinear adaptive approach is employed. Moreover, a Time Delay Feedback Controller (TDFC) is implemented to stabilize Unstable Periodic Orbits (UPOs). Also multiple scales method to analyze chaotic behavior and types of fixed points in ferroresonance occurrence at voltage transformers considering different types of core loss models is applied. In the literature ferroresonance phenomenon in voltage transformers is proved to be classified in chaotic dynamics systems. In this contribution, chaos occurs in the system from a sequence of Period Doubling Bifurcation (PDB). This phenomenon consists of different types of bifurcations such as Period Doubling Bifurcation (PDB), Saddle Node Bifurcation (SNB), Hopf Bifurcation (HB) and chaos. Dynamic analysis of ferroresonant circuit is performed using bifurcation theory. bifurcation diagrams and phase plane diagrams are illustrated using a continuation method for linear and nonlinear core loss models. For analyzing ferroresonance phenomenon, Lyapunov exponents are calculated using multiple scales method and feigenbaum numbers are obtained. Bifurcation diagrams illustrate variation of parameter control and as a result chaos is created and increased in the system.

Resistive Ferroresonance Limiter for Potential Transformers

The ferroresonance or nonlinear resonance is a complex phenomenon, which may cause overvoltage in the electrical power system and endangers the system reliability and operation. The ability to predict the ferroresonance in the transformer depends on the accuracy of the transformer model used. In this paper, the effect of the new suggested ferroresonance limiter on the control of the chaotic ferroresonance and duration of chaotic transients in a potential transformer including nonlinear core losses is studied. To study the proposed ferroresonance limiter, a single phase 100 VA, 275 kV potential transformer is simulated. The magnetization characteristic of the potential transformer is modeled by a single-value two-term polynomial. The core losses are modeled by third order power series in terms of voltage and include core nonlinearities. The simulation results show that the ferroresonance limiter has a considerable effect on the ferroresonance overvoltage.

Ferroresonance of Power Transformers Considering Non-linear Core Losses and Metal Oxide Surge Arrester Effects

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.

Ferroresonance in Voltage Transformer ConsideringLinear and Nonlinear Core Losses Effect

Ferroresonance is a complex electrical phenomenon, which can cause overvoltages in the electrical power system and endangers the system reliability and continuous safe operating. This paper studies the effect of linear and nonlinear core losses on the chaotic ferroresonance in a voltage transformer. 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 nonlinear core losses on the voltage transformer, exhibits a great effect on ferroresonance overvoltages. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance voltages has been obtained and presented.

Effect of Metal Oxide Surge Arrester on Ferroresonance inVoltage Transformer Including Nonlinear Core Losses

This paper studies the effect of Metal Oxide Surge Arrester (MOSA) on ferroresonance overvoltage transformer (VT) considering nonlinear core losses effect. It is expected that MOSA generally cause ferroresonance 'dropout'. Time-domain study has been done to study this effect. Simulation has been done on a voltage transformer rated 100VA, 275 kV. The magnetization characteristic of the transformer is modelled by a single-value two-term polynomial with order seven. The core loss is modelled by nonlinear resistance. The simulation results reveal that connecting the MOSA in parallel to the VT exhibits a great controlling effect on ferroresonance overvoltages. Phase plane, voltage waveforms, along with bifurcation diagrams are also derived. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance overvoltages has been obtained and presented.

Damping Nonlinear Oscillations in Potential Transformers Including Hysteresis Effect

In this work, an overview of available papers are provided, at first ferroresonance phenomenon is introduced and then various type of ferroresonance in a potential transformer is simulated, then effect of neutral earth resistance on the onset of chaotic ferroresonance and duration of chaotic transient in a potential transformer including nonlinear core losses has been studied. It is expected that this resistance generally cause controlling ferroresonance overvoltages. The proposed approach was implemented using MATLAB, and results are presented. For confirmation this aspect simulation has been done on a one phase potential transformer rated 100VA, 275kV. Core losses is modelled in terms of voltage and includes nonlinearities in core losses .The simulation results show that connecting the neutral earth resistance on the system configuration, shows a great controlling effect on ferroresonance overvoltages.

Nonlinear Oscillation in Potential Transformers Connected Controlling Circuit

In this work at first ferroresonance phenomenon is introduced and then various type of ferroresonance overvoltages in a potential transformer is simulated. Then effect of neutral earth resistance on controlling these oscillations in the case of nonlinear core losses has been studied. Core losses in the potential transformer are modelled by third order power series in terms of voltage and include nonlinearities in core losses. It is expected that neutral earth resistance generally can cause ferroresonance 'dropout'. For confirmation this aspect Simulation has been done on a one phase potential transformer rated 100VA, 275kV. The simulation results show that connecting the neutral earth resistance on the system configuration, shows a great controlling effect on ferroresonance oscillation.

Circuit Breaker Shunt Resistance Effect on Ferroresonancein Voltage Transformer Including Nonlinear Core Losses

Ferroresonance is a nonlinear resonance, which may cause overvoltages in the electrical power system. This paper studies the effect of circuit breaker shunt resistance on the control of ferroresonance in a voltage transformer while the core losses of the VT 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 overvoltages. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance overvoltages has been obtained and presented.

Impact of Core Loss Non-linearity on Stability Domain of Ferroresonance

Iron losses strongly influence ferroresonance behavior of power transformers. While a jump-up is the characteristic of the non-linear magnetizing branch, the jump-down phenomenon can only be described when losses or loads are considered. In this article, the impact of core losses (constant resistance or non-linear resistancce) on the turning points of the bifurcation diagram of a ferroresonance circuit is investigated by a developed 2-D bifurcation diagram. The sensitivity of solutions with respect to the circuit parameters are analyzed and discussed. It is shown that the left-side turning point is more affected by the non-linear core loss model than the right side is. Based on the developed method, an operational guideline for the range of values of the load that avoids the jump between steady-state solutions and ferroresonance overvoltages with different source voltage amplitudes is provided. The results obtained by analytical approach are compared with time domain simulations.

Numerical and experimental analysis of core loss modeling for period-1 ferroresonance

Iron losses strongly influence ferroresonance behavior of power transformers. Core losses have a great importance on the lower limit of the voltage source interval where a fundamental ferroresonance regime exists. This paper is concerned with comparing analytical nonlinear core loss models implemented to fundamental ferroresonance studies. A simple single-phase model is used to represent the case of ferroresonance between a transformer and a capacitor. Comparisons are made between the analytical methods and corresponding experimental results. Simulation results show that estimation of the core losses with enough accuracy determines the second bifurcation point, whatever the core loss model is. Copyright © 2010 John Wiley & Sons, Ltd.

Analysis of ferroresonance in a neutral grounding system with nonlinear core loss

The chaotic behaviour exhibited by a typical ferroresonant circuit in a neutral grounding system is investigated in this paper. In most earlier ferroresonance studies the core loss of the power transformer was neglected or represented by a linear resistance. However, this is not always true. In this paper the core loss of the power transformer is modelled by a third order series in voltage and the magnetization characteristics of the transformer are modelled by an 11th order two-term polynomial. Extensive simulations are carried out to analyse the effect of nonlinear core loss on transformer ferroresonance. A detailed analysis of simulation results demonstrates that, with the nonlinear core loss model used, the onset of chaos appears at a larger source voltage and the transient duration is shorter.

A generalized dynamic circuit model of magnetic cores for low- and high-frequency applications. I. Theoretical calculation of the equivalent core loss resistance

This paper describes the theoretical calculation of the equivalent core loss resistance for a dynamic magnetic core loss model. The equivalent core loss resistance incorporates the effects of both the classical eddy current and anomalous losses. Derivation of a generalized nonlinear core loss resistance expression is presented. This new equivalent core loss resistance can be incorporated into a generalized dynamic magnetic core circuit model suitable for low and high frequency applications.

Electronic transformers using amorphous material

An electronic current transformer uses an amorphous material core transformer which operates into a virtually zero ohm load by use of feedback type operational amplifiers. The output voltage is directly proportional to the primary current of the transformer. Due to the very low flux density created by virtually short circuiting the CT, the nonlinear effects and core losses are reduced substantially. An advantage of the electronic transformer is, among others, that a current transformer of reduced size may be used. Application of the amorphous alloys in small electronic current transformers and other devices appear to be justified where the design optimization can make use of (1) the lower cost expected from the amorphous alloys, or (2) their lower losses and higher permeabilities compared to the crystalline Fe-Co and Fe-Si alloys. Test results have shown that the amorphous material core transformer using an active load has somewhat lower performance than Fe-Ni (HyMu 80) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sup> core transformer of the same size but the amorphous core transformer is significantly superior to the Fe-Si core transformer.