Luciano Martins Neto

Power quality impact on performance and associated costs of three-phase induction motors

This paper aims to present investigation results related to induction motors operation under nonideal supply conditions. The motors are of squirrel cage type and the nonideal conditions are associated to harmonics, unbalances, voltage sag and swell, etc. The studies are carried out using time domain modeling and the SABER simulator. Using this approach, computational results are derived in order to compare the nonideal motor performance to the ideal ones so that the real supply condition effect upon the motor behavior can be highlighted. In addition to technical aspects, the power quality impact on energy and financial waste and is also considered.

Parameters Estimation of a Horizontal Multilayer Soil Using Genetic Algorithm

This paper presents an optimization methodology by using a genetic algorithm (GA) to obtain the parameters of a soil that can be represented in a multilayer structure. The method uses a curve of experimental apparent resistivity obtained from measurements made in the soil. This experimental curve is compared with another curve of apparent resistivity of the soil, theoretical, produced by the GA. The theoretical curve is based on Sundes Algorithm and is exactly the inverse process used for the horizontal stratification of the soil in multilayers. With both curves in hand, the error produced in the process of soil stratification can be estimated. From the estimated errors, the parameters are optimized. The main difference of this method, comparing the already developed methods is just that, besides optimizing the resistivities ρi and the thicknesses hi of each soil layer, the proposed method also optimizes the layers quantity, seeking the best soil stratification. The obtained results of this paper are compared with other soil stratification methods.

Electromagnetic Problems Solving by Conformal Mapping: A Mathematical Operator for Optimization

Having the property to modify only the geometry of a polygonal structure, preserving its physical magnitudes, the Conformal Mapping is an exceptional tool to solve electromagnetism problems with known boundary conditions. This work aims to introduce a new developed mathematical operator, based on polynomial extrapolation. This operator has the capacity to accelerate an optimization method applied in conformal mappings, to determinate the equipotential lines, the field lines, the capacitance, and the permeance of some polygonal geometry electrical devices with an inner dielectric of permittivity . The results obtained in this work are compared with other simulations performed by the software of finite elements method, Flux .

Induction motors thermal behaviour and life expectancy under non-ideal supply conditions

This paper deals with thermal behaviour analysis of three-phase induction motors under nonideal supply conditions. The motors are of squirrel cage type and the nonideal conditions are associated to harmonics, unbalances, voltage sag and swell, etc. The studies are carried out using a comprehensive methodology which handles electrical, mechanical and thermal models in a simultaneous way. The approach is then implemented into a time domain program known as the SABER simulator. Computational studies are then performed to evaluate motor temperature rise and life reduction under nonideal conditions.

Horizontal Multilayer Soil Parameter Estimation Through Differential Evolution

This paper presents a methodology to represent an unknown soil through a stratified horizontal multilayer soil model. It uses the experimental electrical apparent resistivity curve, obtained by measurements on the ground, using a 4-wire earth ground resistance tester kit, along with some calculations. This curve is then compared with the theoretical electrical apparent resistivity curve, obtained through calculations over a horizontally stratified soil, whose parameters are known. The horizontal multilayer soil model parameters, such as number of layers, in addition to the resistivity and thickness of each layer, are optimized by the Differential Evolution algorithm. In order for both apparent resistivity curves to get close, the model can be a representation of the unknown soil. We also present methodologies to verify the theoretical apparent resistivity calculations, by extending the characteristic curve approximation, and to improve error peaks between the apparent resistivity curves, by giving opportunities for other more uniform solutions to excel. A case study uses experimental data from other methods for further comparisons.

Three-phase asymmetrical induction motor fed by a single-phase distribution system-detailed mathematical model

This paper focuses on a time domain model of a three-phase asymmetrical induction motor fed by a single-phase distribution system. A low cost solution for a common problem in Brazilian rural areas. The main effort in this case is to obtain a feedback on the design of asymmetrical three-phase induction motors with single-phase feeding intended to be a low cost and useful option for rural applications. Modeling was validated by the design and construction os a 2 HP asymmetrical three-phase induction motor, in this case theoretical analysis is compared with experimental results. This comparison allows us to obtain conclusions on this machines global behavior under full-load operation.

Experimental Analysis of Harmonic Distortion in Isolated Induction Generators

The use of induction generator, replacing the continuous and synchronous generators, has proved to be an interesting solution for the supply of electricity in remote areas where the supply through a distribution network is not economically viable. In some cases the use of this type of machine has shown itself to be convenient, where it is associated with unconventional power systems, such as wind and hydro generation small. In these isolated systems is common to use cage induction generators with excitation capacitors, known as self excited induction generators. Allied to this, there has been an increase in the number of non-linear loads, at all levels of electricity consumption. Thus, it becomes necessary to study experimentally the harmonic distortion of voltage and current in this type of generator, which can supply non-linear loads that may be present in these remote areas.

Modeling validation of Salient Pole Synchronous Machines from experimental inductances

In this paper, a computer simulation of the Salient Pole Synchronous Machine (SPSM) is presented. This simulation employs a modeling based on the machine self and mutual inductance curves, determined from a methodology, not presented here. These methodology applies the experimental volt-ampere method to obtaining the inductances curves. From these inductance data, using a mathematical methodology, are obtained the derivative inductances curves. The simulated results are confronted with the experimental currents and voltages measured in tests, for purposes of validation of the SPSM modeling from the experimental inductances.

Effects of magnetic saturation on induction machines driven by static converters

The effects of magnetic saturation on the operation of induction motors driven by static converters are analyzed. A mathematical model based on magnetic harmonic functions is used to account for saturation. Distortions on the air gap flux due to non-linear magnetic characteristics lead to appearance of space harmonics in the resultant flux density distribution. This causes specific distortions in stator and rotor time quantities, which are different from those due to static converter. Operation with six pulse and sinusoidal PWM converters under saturated conditions is considered. Comparisons of experimental and simulated results are presented and found to be in very good agreement.

New linear flux model for three-phase induction motors - comparative analysis with abc and dq0 models

This paper present a new linear flux model for the three-phase induction machine. It was originally developed to consider the magnetic saturation but in its linear version it has shown advantage over the traditional ABC and dq0 models in reducing considerably the simulation time while delivering the same degree of accuracy. An extensive comparison with the traditional methods is made and results are shown.