Mauricio Caldora Costa - Academia.edu (original) (raw)

Papers by Mauricio Caldora Costa

IEE Proceedings - Science, Measurement and Technology, 2004

ABSTRACT The experimental design method is applied to the construction of a response surface base... more ABSTRACT The experimental design method is applied to the construction of a response surface based on diffuse elements as preliminary steps in the optimisation process of the magnetic torque of a switched reluctance motor. The experimental design method is used to find and choose the most significant parameters related to the magnetic torque of the motor, reducing the number of parameters to be optimised. The diffuse element method is used to build a response surface that represents an approximation of the real objective function. The optimised values of the parameters are obtained after the application of genetic algorithms in the response surface, reducing drastically the final computation time.

IEEE Transactions on Magnetics, 2002

A new algorithm to obtain the response surface of objective functions is presented. The diffuse-e... more A new algorithm to obtain the response surface of objective functions is presented. The diffuse-element method and quadtrees are used in the implementation of this algorithm. The approximation of a two-parameter analytical function and the optimization of a switched reluctance motor are performed to show the robustness of this new approach.

Revue internationale de génie électrique, 2001

International audienc

Este artigo apresenta os estudos realizados para desenvolver um modelo tridimensional em elemento... more Este artigo apresenta os estudos realizados para desenvolver um modelo tridimensional em elementos finitos de um transformador de potencia de 30/40 MVA, verificando o seu comportamento termico em funcao da temperatura ambiente e de sua curva de carga, comparando os resultados de simulacao com valores obtidos a partir de medicoes de temperatura realizadas no topo do oleo, no ponto quente dos enrolamentos e em pontos externos do tanque e dos radiadores. A modelagem desenvolvida faz parte de um conjunto de acoes e pesquisas realizadas com o objetivo de determinar os limites de carregamento para as unidades transformadoras de forma otimizada, de modo a estabelecer um criterio menos conservativo para a expansao do sistema distribuidor, com consequente reducao de custos no Plano de Obras da empresa. This paper presents a research to develop a three-dimensional model in finite elements applied a 30/40 MVA power transformer, verifying its thermal behavior as a function of ambient temperatur...

Acta Polytechnica, 2020

Power transformers are the most common equipment in an electric power system, which has been manu... more Power transformers are the most common equipment in an electric power system, which has been manufactured in the last decade. However, overheating can damage them, considerably reducing their operation lives, which may cause economic losses to the power utilities. The motivation of this paper is to investigate the time and power overload limits that a power transformer can be subjected to and how it will impact its temperature. Investments in the grid can be delayed if a transformer can support some overload during some momentary load demand increase. In this context, this paper presents a study of a 30/40MVA power transformer by 3D finite element method (FEM) for coupled thermal-electromagnetic simulations to investigate its thermal behaviour when it is submitted to its nominal load at a steady-state operation and a variable load during a period of one day. The simulations were performed with the commercial software packages Flux 3D and AcuSolve, for electromagnetic and thermal mod...

2009 IEEE International Electric Machines and Drives Conference, 2009

This study addresses a proposal of a bench to test single-phase induction motors and switched rel... more This study addresses a proposal of a bench to test single-phase induction motors and switched reluctance motors with rated power up to 1 hp. The bench was set up so that single-phase induction motor tests meet requirements of IEEE Std. 114-2001 and the Brazilian related Standard (ABNT NBR 5383-2/2008). In addition, the test procedures for reluctance motors comprise sequential steps

Revue internationale de génie électrique, 2001

2004 IEEE/PES Transmision and Distribution Conference and Exposition: Latin America (IEEE Cat. No. 04EX956)

This paper presents a case study related to the electric and magnetic fields generated by an upgr... more This paper presents a case study related to the electric and magnetic fields generated by an upgraded high voltage overhead transmission line in an urban environment. Consideration of risk perception recommends a previous analysis of electric and magnetic fields. A computational model based on charge simulation method to calculate electric field and Biot-Savart law to calculate magnetic field is outlined. Model validation is done by simulation and measuring of electric and magnetic fields on neighborhood of the existing transmission line prior upgrade. Results of simulation of electric and magnetic fields with the new transmission line configuration were assessed to verify compliance with exposure limits recommended by World Health Organization. Magnetic and electric fields were measured considering the new configuration of transmission line.

IEEE Latin America Transactions, 2013

ABSTRACT The power transformer thermal response related to a load curve can be verified by a trid... more ABSTRACT The power transformer thermal response related to a load curve can be verified by a tridimensional model using finite elements. This paper presents the modeling and the software developed for this purpose and compares the results with local tests data of two critical points - the top of the oil and the winding hot spot. Using the technique described, the maximum load limit of power transformers can be determinate, and operation costs and system expansion can be analyzed.

IEEE Transactions on Magnetics, 2000

Abstract—In the last few years, several papers considering the Finite Element Method coupled with... more Abstract—In the last few years, several papers considering the Finite Element Method coupled with Electric Circuits were pub-lished. Many of these works have been used the theory of Mesh Analysis to analyze the electric circuit. However, when we use a circuit with many current ...

IEEE Transactions on Magnetics, 2001

This paper presents a new method to accelerate the optimization process of stochastic methods. Th... more This paper presents a new method to accelerate the optimization process of stochastic methods. This method is an adaptive procedure of the Diffuse Element Approximation, used to approximate the objective function. The robustness of this new approach is verified on a two parameters function optimization and the Problem 25 of TEAM Workshop.

IEEE Transactions on Magnetics, 2004

This paper deals with the use of the Kriging models for objective function approximations and the... more This paper deals with the use of the Kriging models for objective function approximations and their use on electromagnetic device optimization. The models are compared with some radial basis function neural networks and with the diffuse element method. Comparative tests are done on an analytical function and on the TEAM workshop problem 25.

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2003

Abstract: This paper compares three different radial basis function neural networks, as well as t... more Abstract: This paper compares three different radial basis function neural networks, as well as the diffuse element method, according to their ability of approximation. This is very useful for the optimization of electromagnetic devices. Tests are done on several analytical functions and on the TEAM workshop problem 25.

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 2005

PurposeThe design of electrical machines includes the computation of several requirements and, in... more PurposeThe design of electrical machines includes the computation of several requirements and, in general, the improvement of one requirement implies in a degradation of another one: this is a typical multi‐objective scenario. The paper focuses on the multi‐optimization analysis of a special switched reluctance motor.Design/methodology/approachTwo design requirements were analyzed: the average torque and the ripple torque. The electromagnetic field computation was performed by the finite element method and the torque was computed by the Coulomb's Virtual Work for several positions. This allows us to calculate the average torque and the ripple torque. Three different methods were used to obtain the Pareto set: a min‐max approach, the non‐dominated sorting genetic algorithm (NSGA) and the strength Pareto evolutionary algorithm (SPEA). In order to save the computation time, the objective functions (the average torque and the ripple torque) were replaced with surrogate functions. Kr...

This paper proposes an original approach for modelling ferromagnetic sheet in inverse problem. It... more This paper proposes an original approach for modelling ferromagnetic sheet in inverse problem. It is realised with layers of tangential dipoles. This distribution is built thanks to measurements on sensors located in the interior of the device. The problem being ill-posed, we propose a new regularisation method to obtain a physical solution by injection of direct problem (DPI). It's then easy to compute the field everywhere around the device where sensors can't be placed. Moreover, the permanent magnetisation of the shell can be identified and systems with fewer equations than unknowns can be solved.

I. INTRODUCTION he application of stochastic methods in the optimization of electromagnetic devic... more I. INTRODUCTION he application of stochastic methods in the optimization of electromagnetic devices analysed by Finite Element Method can require a high computational time, due to the high number of evaluations of the objective function. A solution for this problem consists ...

IEEE Transactions on Magnetics, 2000

This paper presents a structure of classes based on Object-Oriented Programming, which allows the... more This paper presents a structure of classes based on Object-Oriented Programming, which allows the development of an Optimization Library. In this library, deterministic and stochastic optimization algorithms are considered, as well as algorithms that work with constrained or unconstrained objective functions. First of all, we will present the characteristics of some main optimization methods used in the last years, mainly in the electromagnetic area. Later on, based on these characteristics, we will show the classes created for the implementation of this optimization library. Finally, we will present the communication architecture used for data exchange between this library and a Finite Element Method software.

IEE Proceedings - Science, Measurement and Technology, 2004

ABSTRACT The experimental design method is applied to the construction of a response surface base... more ABSTRACT The experimental design method is applied to the construction of a response surface based on diffuse elements as preliminary steps in the optimisation process of the magnetic torque of a switched reluctance motor. The experimental design method is used to find and choose the most significant parameters related to the magnetic torque of the motor, reducing the number of parameters to be optimised. The diffuse element method is used to build a response surface that represents an approximation of the real objective function. The optimised values of the parameters are obtained after the application of genetic algorithms in the response surface, reducing drastically the final computation time.

IEEE Transactions on Magnetics, 2002

A new algorithm to obtain the response surface of objective functions is presented. The diffuse-e... more A new algorithm to obtain the response surface of objective functions is presented. The diffuse-element method and quadtrees are used in the implementation of this algorithm. The approximation of a two-parameter analytical function and the optimization of a switched reluctance motor are performed to show the robustness of this new approach.

Revue internationale de génie électrique, 2001

International audienc

Este artigo apresenta os estudos realizados para desenvolver um modelo tridimensional em elemento... more Este artigo apresenta os estudos realizados para desenvolver um modelo tridimensional em elementos finitos de um transformador de potencia de 30/40 MVA, verificando o seu comportamento termico em funcao da temperatura ambiente e de sua curva de carga, comparando os resultados de simulacao com valores obtidos a partir de medicoes de temperatura realizadas no topo do oleo, no ponto quente dos enrolamentos e em pontos externos do tanque e dos radiadores. A modelagem desenvolvida faz parte de um conjunto de acoes e pesquisas realizadas com o objetivo de determinar os limites de carregamento para as unidades transformadoras de forma otimizada, de modo a estabelecer um criterio menos conservativo para a expansao do sistema distribuidor, com consequente reducao de custos no Plano de Obras da empresa. This paper presents a research to develop a three-dimensional model in finite elements applied a 30/40 MVA power transformer, verifying its thermal behavior as a function of ambient temperatur...

Acta Polytechnica, 2020

Power transformers are the most common equipment in an electric power system, which has been manu... more Power transformers are the most common equipment in an electric power system, which has been manufactured in the last decade. However, overheating can damage them, considerably reducing their operation lives, which may cause economic losses to the power utilities. The motivation of this paper is to investigate the time and power overload limits that a power transformer can be subjected to and how it will impact its temperature. Investments in the grid can be delayed if a transformer can support some overload during some momentary load demand increase. In this context, this paper presents a study of a 30/40MVA power transformer by 3D finite element method (FEM) for coupled thermal-electromagnetic simulations to investigate its thermal behaviour when it is submitted to its nominal load at a steady-state operation and a variable load during a period of one day. The simulations were performed with the commercial software packages Flux 3D and AcuSolve, for electromagnetic and thermal mod...

2009 IEEE International Electric Machines and Drives Conference, 2009

This study addresses a proposal of a bench to test single-phase induction motors and switched rel... more This study addresses a proposal of a bench to test single-phase induction motors and switched reluctance motors with rated power up to 1 hp. The bench was set up so that single-phase induction motor tests meet requirements of IEEE Std. 114-2001 and the Brazilian related Standard (ABNT NBR 5383-2/2008). In addition, the test procedures for reluctance motors comprise sequential steps

Revue internationale de génie électrique, 2001

2004 IEEE/PES Transmision and Distribution Conference and Exposition: Latin America (IEEE Cat. No. 04EX956)

This paper presents a case study related to the electric and magnetic fields generated by an upgr... more This paper presents a case study related to the electric and magnetic fields generated by an upgraded high voltage overhead transmission line in an urban environment. Consideration of risk perception recommends a previous analysis of electric and magnetic fields. A computational model based on charge simulation method to calculate electric field and Biot-Savart law to calculate magnetic field is outlined. Model validation is done by simulation and measuring of electric and magnetic fields on neighborhood of the existing transmission line prior upgrade. Results of simulation of electric and magnetic fields with the new transmission line configuration were assessed to verify compliance with exposure limits recommended by World Health Organization. Magnetic and electric fields were measured considering the new configuration of transmission line.

IEEE Latin America Transactions, 2013

ABSTRACT The power transformer thermal response related to a load curve can be verified by a trid... more ABSTRACT The power transformer thermal response related to a load curve can be verified by a tridimensional model using finite elements. This paper presents the modeling and the software developed for this purpose and compares the results with local tests data of two critical points - the top of the oil and the winding hot spot. Using the technique described, the maximum load limit of power transformers can be determinate, and operation costs and system expansion can be analyzed.

IEEE Transactions on Magnetics, 2000

Abstract—In the last few years, several papers considering the Finite Element Method coupled with... more Abstract—In the last few years, several papers considering the Finite Element Method coupled with Electric Circuits were pub-lished. Many of these works have been used the theory of Mesh Analysis to analyze the electric circuit. However, when we use a circuit with many current ...

IEEE Transactions on Magnetics, 2001

This paper presents a new method to accelerate the optimization process of stochastic methods. Th... more This paper presents a new method to accelerate the optimization process of stochastic methods. This method is an adaptive procedure of the Diffuse Element Approximation, used to approximate the objective function. The robustness of this new approach is verified on a two parameters function optimization and the Problem 25 of TEAM Workshop.

IEEE Transactions on Magnetics, 2004

This paper deals with the use of the Kriging models for objective function approximations and the... more This paper deals with the use of the Kriging models for objective function approximations and their use on electromagnetic device optimization. The models are compared with some radial basis function neural networks and with the diffuse element method. Comparative tests are done on an analytical function and on the TEAM workshop problem 25.

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2003

Abstract: This paper compares three different radial basis function neural networks, as well as t... more Abstract: This paper compares three different radial basis function neural networks, as well as the diffuse element method, according to their ability of approximation. This is very useful for the optimization of electromagnetic devices. Tests are done on several analytical functions and on the TEAM workshop problem 25.

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 2005

PurposeThe design of electrical machines includes the computation of several requirements and, in... more PurposeThe design of electrical machines includes the computation of several requirements and, in general, the improvement of one requirement implies in a degradation of another one: this is a typical multi‐objective scenario. The paper focuses on the multi‐optimization analysis of a special switched reluctance motor.Design/methodology/approachTwo design requirements were analyzed: the average torque and the ripple torque. The electromagnetic field computation was performed by the finite element method and the torque was computed by the Coulomb's Virtual Work for several positions. This allows us to calculate the average torque and the ripple torque. Three different methods were used to obtain the Pareto set: a min‐max approach, the non‐dominated sorting genetic algorithm (NSGA) and the strength Pareto evolutionary algorithm (SPEA). In order to save the computation time, the objective functions (the average torque and the ripple torque) were replaced with surrogate functions. Kr...

This paper proposes an original approach for modelling ferromagnetic sheet in inverse problem. It... more This paper proposes an original approach for modelling ferromagnetic sheet in inverse problem. It is realised with layers of tangential dipoles. This distribution is built thanks to measurements on sensors located in the interior of the device. The problem being ill-posed, we propose a new regularisation method to obtain a physical solution by injection of direct problem (DPI). It's then easy to compute the field everywhere around the device where sensors can't be placed. Moreover, the permanent magnetisation of the shell can be identified and systems with fewer equations than unknowns can be solved.

I. INTRODUCTION he application of stochastic methods in the optimization of electromagnetic devic... more I. INTRODUCTION he application of stochastic methods in the optimization of electromagnetic devices analysed by Finite Element Method can require a high computational time, due to the high number of evaluations of the objective function. A solution for this problem consists ...

IEEE Transactions on Magnetics, 2000

This paper presents a structure of classes based on Object-Oriented Programming, which allows the... more This paper presents a structure of classes based on Object-Oriented Programming, which allows the development of an Optimization Library. In this library, deterministic and stochastic optimization algorithms are considered, as well as algorithms that work with constrained or unconstrained objective functions. First of all, we will present the characteristics of some main optimization methods used in the last years, mainly in the electromagnetic area. Later on, based on these characteristics, we will show the classes created for the implementation of this optimization library. Finally, we will present the communication architecture used for data exchange between this library and a Finite Element Method software.