Sergio Luiz Schubert Severo - Academia.edu (original) (raw)

Papers by Sergio Luiz Schubert Severo

Research paper thumbnail of RF environment optimization using UWB monocone antenna

Simulations and measurements of the reflections using a UWB monocone antenna in closed environmen... more Simulations and measurements of the reflections using a UWB monocone antenna in closed environment are shown in this paper. A circular brick wall was constructed to perform the experiments. The monocone antenna was designed and optimized using the Antenna Magus software. This antenna shows a low VSWR from 500 to 4000 MHz. When the frequency of operation is specified and the brick relative constant is knows, the wall thickness can be designed to minimize reflections and improve transmission through the walls.

Research paper thumbnail of Active power control of hydro-electric power unit auxiliary synchronous generator connected to distribution systems

ABSTRACT This paper presents initial project and test results of an active power control scheme d... more ABSTRACT This paper presents initial project and test results of an active power control scheme development for auxiliary synchronous generators of an AES-Distribution System connected Hydraulic Generation Unit. An open loop control system using TCSC switched by IGBT's is proposed to compensate the inductive impedance of the synchronous generator and control the active power injection. Several switching angles were evaluated at different compensation levels and simulations are presented to analyze the effectiveness and robustness of the proposed controller project.

Research paper thumbnail of T-slot PIFA with excitation of the ground plane resonant modes and considerations of the interaction between antenna, mobile handset and user's head

2013 SBMO/IEEE MTT-S International Microwave & Optoelectronics Conference (IMOC), 2013

This paper presents a T-slot planar inverted F antenna (PIFA) for wireless mobile communications ... more This paper presents a T-slot planar inverted F antenna (PIFA) for wireless mobile communications GSM/UMTS/WCDMA systems. A modified ground plane is used to increase the bandwidth. A prototype is implemented and the differences in performance of the antenna with and without the presence of the mobile handset and the user's head are estimated. The simulations are performed using the finite difference time domain (FDTD) method.

Research paper thumbnail of Acquiring a Knowledge Base of Continuous Processes through a Distributed System

This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes thro... more This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes through a distributed system. The proposed methodology combines MKB and case-based reasoning (CBR) for adaptive knowledge base creation, maintenance and updating trough the use of an architecture with the following aspects: i) distributed architecture network; ii) real-time operation; iii) advanced visual interface. Although originally developed for use in hydroelectric power plants it is useful for other industrial processes in mission-critical with high cost of interruption. This work presents the system requirements, the aspects of the case base formation, the CBR cycle and the believe network.

Research paper thumbnail of A new method to minimize harmonic components of PWM signals based on lagrange multipliers

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

ABSTRACT With the evolution observed nowadays in power electronics systems, frequency converters ... more ABSTRACT With the evolution observed nowadays in power electronics systems, frequency converters are increasingly used in the grid. However, due to switching techniques employed, the harmonic distortion of the resulting signals became an important parameter to be considered in the design of such converters. For this reason, special attention has been given to the techniques of pulse width modulation (PWM) aimed at reducing the harmonic content. This paper proposes a new methodology for the determination of the PWM pulses, based on the application of nonlinear numerical optimization technique using the Lagrange algorithm for minimizing an objective function. The application of this new technique enables the minimization of the total harmonic distortion (THD) at the same time that restrictions are imposed on the amplitudes of harmonic components of interest. Numerical results demonstrate the potentiality of the proposed methodology.

Research paper thumbnail of Active power regulation of auxiliary generation units in hydroelectric power plants using power electronic switching

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

This paper presents the initial results of a research project that aims to develop a control syst... more This paper presents the initial results of a research project that aims to develop a control system for active power regulation in synchronous auxiliary generators connected to hydraulic generation units. In this sense, the developed system is based on the compensation of the inductive impedance of the auxiliary generator using TCSC switched by IGBT0s. The control of IGBT0s firing angle is achieved by symmetric pulses generated by a PWM module. The proposed system was implemented and tested digitally in Simulink/MatLab environment considering several active power values demanded by an auxiliary distribution system of 400VCA. The promising results obtained in these simulations show the efficiency and robustness of the proposed methodology.

Research paper thumbnail of A supervisory system for real-time oscillography of synchronous generators

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

This paper presents an innovative proposal for a SCADA system platform, integrating oscillographi... more This paper presents an innovative proposal for a SCADA system platform, integrating oscillographic capabilities to the set of functions found in standard supervisory and control systems. The proposed SCADA system was developed using C++ language, targeted to x86-64/Windows 7 processing platforms, and is based on multithreading programming. The resulting system has a low implementation cost. The hardware architecture, along with the adopted software tools, satisfactorily meets all the requirements originally planned for the proposed system.

Research paper thumbnail of Synchronization method for synchronous generator based on UPFC

2013 IEEE Grenoble Conference, 2013

ABSTRACT This paper presents a technique for synchronizing synchronous generators without speed c... more ABSTRACT This paper presents a technique for synchronizing synchronous generators without speed control. The proposed construction is under development in a research project which aims to control auxiliary synchronous generators in a hydroelectric power unit. An UPFC device is used to achieve the synchronism of the synchronous generator with the power system. Simulation with different phases angles and voltage magnitude are presented to demonstrate the effectiveness and robustness of the proposed technique.

Research paper thumbnail of Architecture of a distributed system for acquiring knowledge in supporting decision making in operation/maintenance of electric power plants

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes thro... more This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes through a distributed system. The proposed methodology combines MKB and case-based reasoning (CBR) for adaptive knowledge base creation, maintenance and updating trough the use of an architecture with the following aspects: i) distributed architecture network; ii) real-time operation; iii) advanced visual interface. Although originally developed for use in hydroelectric power plants it is useful for other industrial processes in mission-critical with high cost of interruption. This work presents the system requirements, the aspects of the case base formation, the CBR cycle and the believe network.

Research paper thumbnail of Cartas De Smith Digitais Para a Aprendizagem Do Projeto De Osciladores e Amplificadores De Micro-Ondas

Proceedings of the L Brasilian Congress of Engineering Education

Research paper thumbnail of Aquametria por microondas : desenvolvimento de transdutor em microfita

Este trabalho apresenta uma metodologia para o desenvolvimento de transdutor de microondas para a... more Este trabalho apresenta uma metodologia para o desenvolvimento de transdutor de microondas para a mensuração de umidade em produtos agrícolas com a utilização de estruturas planares em microfita. O termo aquametria é definido na literatura como a área da instrumentação responsável por mensurar a quantidade de água presente em sólidos e líquidos via identificação de suas propriedades dielétricas. São apresentados alguns aspectos relativos à aquametria, seguidos do modelo matemático e numérico da interação das ondas eletromagnéticas no meio dielétrico com perdas. O modelo matemático é então especializado para dar conta de uma microfita com uma amostra úmida superposta. A partir desses resultados, são apresentadas três propostas de transdutores que buscam mensurar a permissividade dielétrica complexa efetiva do conjunto microfita mais amostra. Os transdutores propostos são então simulados com a aplicação do método de diferenças finitas no domínio tempo, objetivando não só verificar a q...

Research paper thumbnail of Instrumented Synchronous Feedback Workbench, Learning Object for the Electrical Machines Laboratory

2020 IEEE Global Engineering Education Conference (EDUCON), 2020

Seeking to meet the significant learning needs in the electrical machine laboratory, a workbench ... more Seeking to meet the significant learning needs in the electrical machine laboratory, a workbench with two small synchronous machines (low cost BLDC – Brushless Direct Current motors) is developed. They are mechanically and electrically coupled. Such a configuration is known as synchronous feedback or back-to-back load testing. A metalworking rotary table varies the mechanical power angle (torque angle) between machines. A real time SCADA – Supervisory Control and Data Acquisition, monitors the speed of rotation, voltages and currents in the time domain, the voltage and current phasors and acts on the machines drive. The power angle is calculated from the phasor diagram. The student interacts with the equipment by setting it in motion, accelerating the machines, and varying the mechanical angle through the rotary table. It can then differentiate the operation of machines such as generator and motor, the variation in load caused by the power angle between them, the synchronism, the power factor and the power angle. Progressively, and starting from the student’s action on the object of study, all concepts related to synchronous machines are learned. The workbench is low cost and uses safe voltages for risk free operation.

Research paper thumbnail of A Bayesian network to model a universe of possible drives of residential electrical loads

2018 Simposio Brasileiro de Sistemas Eletricos (SBSE), 2018

In electric power generation and distribution systems, three structures are capable of impacting ... more In electric power generation and distribution systems, three structures are capable of impacting energy quality: generation, distribution and loads. Currently, the diversity of the latter ranges from purely resistive loads such as heating systems to extremely nonlinear loads such as switched electronic power supplies. This has dramatically affected the quality of electric energy. The operation of these loads contributes to the reduction of the power factor of the installation, the injection of harmonic currents in the electrical network and the imbalance of currents and voltages between the phases in the case of three-phase systems. The implementation of a method capable of recognizing electrical loads and identifying them through algorithms can be used to manage the electric energy consumption, contributing a lot to the improvement of the quality of electric energy. In order to deal with uncertainty in the identification of these loads, probability distributions will be applied, wh...

Research paper thumbnail of Specific absorption rate (SAR) in the head of Google glasses and Bluetooth user's

2014 IEEE Latin-America Conference on Communications (LATINCOM), 2014

Two popular wireless communication devices are considered in this paper. Firstly, the Bluetooth w... more Two popular wireless communication devices are considered in this paper. Firstly, the Bluetooth which is one of the most popular mobile accessories and the Google glasses which are a representation of the new futuristic vision. It is well known that the absorption of electromagnetic waves on the human head for a certain period of time may lead to health problems such as headaches, or even worse, brain cancer. The Specific Absorption Rate (SAR) is simulated for three different head models and compared with the available international recommendations. The first model used is the Specific Anthropomorphic Mannequin (SAM phantom), as well as two realistic models of human head (i.e., a 34 years old adult and a 10 years old child). The simulations were performed using the finite difference time domain (FDTD) method and the frequency used to feed the antennas was 2.45 GHz.

Research paper thumbnail of Aquametria por micro-ondas

A medida do teor de umidade de materiais resulta em ganhos econômicos e ambientais ao possibilita... more A medida do teor de umidade de materiais resulta em ganhos econômicos e ambientais ao possibilitar o controle preciso da secagem de produtos agrícolas, de processos de cura e armazenagem, e reduzir perdas de material e consumo de energia. Tal medida pode ser feita através da interação de ondas eletromagnéticas nas frequências de micro-ondas. Apresenta-se o desenvolvimento histórico e o estado da arte dessa área da metrologia que é conhecida por aquametria por micro-ondas. Detalha-se o comportamento das ondas eletromagnéticas em dielétricos, o modelo de espalhamento nas interfaces das amostras, a relação entre a permissividade complexa e a umidade, métodos para a determinação da permissividade, instrumentos, sistemas e aspectos metrológicos da cadeia de medição para espectroscopia dielétrica. Dois novos métodos, com equações explícitas originais para a determinação da permissividade são obtidos. As novas equações resultam em incerteza menor que os métodos clássicos. Uma nova metodologia, através do método de Monte Carlo, é empregada para a avaliação das mesmas. Conclui-se que o desenvolvimento da aquametria passa, necessariamente, pelo aperfeiçoamento dos instrumentos e métodos para determinação da permissividade dos materiais.The measurement of moisture content of materials results in economic and environmental gains. Monitoring drying and curing of materials prevents loss of products and waste of energy. This can be done through the interaction of electromagnetic waves at microwave frequencies. This dissertation presents the historical development and the state-of-the-art in aquametry, the behavior of electromagnetic waves in dielectrics, sample interface scattering model, the relationship between the complex permittivity and moisture, methods for determining permittivity, instruments and metrological aspects of the measurement chain, and some instruments for dielectric spectroscopy. Two new methods, capable of providing explicit equation for the permittivity, are obtained and the Monte Carlo method is applied to determine their uncertainty. The new equations have lower uncertainty than the classic methods. The general conclusion is that the development of instrumentation and techniques in aquametry must be based in improvements in permittivity measurement

Research paper thumbnail of Non-resonant Permittivity Measurement Methods

Journal of Microwaves, Optoelectronics and Electromagnetic Applications, 2017

The measurement of the dielectric properties of materials has been applied in non-destructive tes... more The measurement of the dielectric properties of materials has been applied in non-destructive tests, humidity measurement, soil analysis and even cancer detection. The methods have been developed for over 70 years based on the interaction of the electromagnetic waves with the material under test. This work presents a general model of scattering parameters for non-resonant methods of transmission/reflection and single-port reflection. Equations for determining permittivity are obtained. New equations for short-circuited load and coupled load in the double reflection method are presented.

Research paper thumbnail of Synchronizing microgrids to the utility through a series compensator

2014 Power Systems Computation Conference, 2014

This paper presents a novel approach to deal with the synchronization of microgrids to the main g... more This paper presents a novel approach to deal with the synchronization of microgrids to the main grid. It is based on the use of a power electronic device derived from the original concept of the SSSC (Static Synchronous Series Compensator). The proposed scheme considers the connection of this device at the point-of-interconnection (POI) of the microgrid to the low voltage side of the substation transformer (main grid). The voltage originated by the series compensator is fully controlled in both amplitude and phase angle ensuring the conditions for the synchronization. The proposed scheme allows a smooth transition between the islanded operation and the grid connected operation overcoming typical problems observed when conventional methods are applied. Numerical results obtained for a hypothetical microgrid show the effectiveness of the proposed approach.

Research paper thumbnail of An integrated end-use scada-oscillography system for power quality analysis in smart grids

2013 IEEE PES Conference on Innovative Smart Grid Technologies (ISGT Latin America), 2013

This paper presents an innovative system (hardware and software) that incorporates the main funct... more This paper presents an innovative system (hardware and software) that incorporates the main functions typically found alone in SCADA, oscillography and advanced metering infrastructure systems. The developed system maintains all the characteristics of a SCADA system, suitable for the operation of a distributed generation, while it incorporates oscillography features and power quality measurements. The functions of oscillography and power quality measurements are shared by both smart grid and distributed generation owner on a bilateral basis. The developed system has a low cost implementation.

Research paper thumbnail of A digital phase-locked-loop for synchronization of single-phase sources with the utility grid

2013 IEEE Grenoble Conference, 2013

ABSTRACT This paper presents an innovative digital phase-locked-loop (PLL) implementation that us... more ABSTRACT This paper presents an innovative digital phase-locked-loop (PLL) implementation that uses a moving average filter with a very high rejection on the fundamental frequency and its harmonics. This PLL is very versatile and can be used for synchronizing single-phase sources, control of drives, among others. Due to its fully digital implementation it has a low cost, short settling time and high immunity to noise, disturbances and harmonic components. The method can be applied directly to microprocessor controllers connected in smart grids. Numerical results confirm the efficiency of the developed PLL.

Research paper thumbnail of Belief Network for Non-Intrusive Load Monitoring Methodology and Implementation

2019 IEEE PES Innovative Smart Grid Technologies Conference - Latin America (ISGT Latin America)

This paper proposes Non-Intrusive Load Monitoring (NILM) technique using Bayesian networks to ide... more This paper proposes Non-Intrusive Load Monitoring (NILM) technique using Bayesian networks to identify which load turn-on in certain condition. Explain how to find the values for the conditional probability tables (CPT’s) and presents a methodology to implement the network structure. The information used in the inference are defined as Boolean variables, related with well-defined thresholds, to then be used in Monte Carlo Markov Chain (MCMC) to infer its probabilities. An interface in LabView was developed to question the system, including the MCMC implementation. The measures and characteristics to identify each specific load are shown, and also the advantages of using changeable thresholds.

Research paper thumbnail of RF environment optimization using UWB monocone antenna

Simulations and measurements of the reflections using a UWB monocone antenna in closed environmen... more Simulations and measurements of the reflections using a UWB monocone antenna in closed environment are shown in this paper. A circular brick wall was constructed to perform the experiments. The monocone antenna was designed and optimized using the Antenna Magus software. This antenna shows a low VSWR from 500 to 4000 MHz. When the frequency of operation is specified and the brick relative constant is knows, the wall thickness can be designed to minimize reflections and improve transmission through the walls.

Research paper thumbnail of Active power control of hydro-electric power unit auxiliary synchronous generator connected to distribution systems

ABSTRACT This paper presents initial project and test results of an active power control scheme d... more ABSTRACT This paper presents initial project and test results of an active power control scheme development for auxiliary synchronous generators of an AES-Distribution System connected Hydraulic Generation Unit. An open loop control system using TCSC switched by IGBT's is proposed to compensate the inductive impedance of the synchronous generator and control the active power injection. Several switching angles were evaluated at different compensation levels and simulations are presented to analyze the effectiveness and robustness of the proposed controller project.

Research paper thumbnail of T-slot PIFA with excitation of the ground plane resonant modes and considerations of the interaction between antenna, mobile handset and user's head

2013 SBMO/IEEE MTT-S International Microwave & Optoelectronics Conference (IMOC), 2013

This paper presents a T-slot planar inverted F antenna (PIFA) for wireless mobile communications ... more This paper presents a T-slot planar inverted F antenna (PIFA) for wireless mobile communications GSM/UMTS/WCDMA systems. A modified ground plane is used to increase the bandwidth. A prototype is implemented and the differences in performance of the antenna with and without the presence of the mobile handset and the user's head are estimated. The simulations are performed using the finite difference time domain (FDTD) method.

Research paper thumbnail of Acquiring a Knowledge Base of Continuous Processes through a Distributed System

This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes thro... more This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes through a distributed system. The proposed methodology combines MKB and case-based reasoning (CBR) for adaptive knowledge base creation, maintenance and updating trough the use of an architecture with the following aspects: i) distributed architecture network; ii) real-time operation; iii) advanced visual interface. Although originally developed for use in hydroelectric power plants it is useful for other industrial processes in mission-critical with high cost of interruption. This work presents the system requirements, the aspects of the case base formation, the CBR cycle and the believe network.

Research paper thumbnail of A new method to minimize harmonic components of PWM signals based on lagrange multipliers

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

ABSTRACT With the evolution observed nowadays in power electronics systems, frequency converters ... more ABSTRACT With the evolution observed nowadays in power electronics systems, frequency converters are increasingly used in the grid. However, due to switching techniques employed, the harmonic distortion of the resulting signals became an important parameter to be considered in the design of such converters. For this reason, special attention has been given to the techniques of pulse width modulation (PWM) aimed at reducing the harmonic content. This paper proposes a new methodology for the determination of the PWM pulses, based on the application of nonlinear numerical optimization technique using the Lagrange algorithm for minimizing an objective function. The application of this new technique enables the minimization of the total harmonic distortion (THD) at the same time that restrictions are imposed on the amplitudes of harmonic components of interest. Numerical results demonstrate the potentiality of the proposed methodology.

Research paper thumbnail of Active power regulation of auxiliary generation units in hydroelectric power plants using power electronic switching

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

This paper presents the initial results of a research project that aims to develop a control syst... more This paper presents the initial results of a research project that aims to develop a control system for active power regulation in synchronous auxiliary generators connected to hydraulic generation units. In this sense, the developed system is based on the compensation of the inductive impedance of the auxiliary generator using TCSC switched by IGBT0s. The control of IGBT0s firing angle is achieved by symmetric pulses generated by a PWM module. The proposed system was implemented and tested digitally in Simulink/MatLab environment considering several active power values demanded by an auxiliary distribution system of 400VCA. The promising results obtained in these simulations show the efficiency and robustness of the proposed methodology.

Research paper thumbnail of A supervisory system for real-time oscillography of synchronous generators

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

This paper presents an innovative proposal for a SCADA system platform, integrating oscillographi... more This paper presents an innovative proposal for a SCADA system platform, integrating oscillographic capabilities to the set of functions found in standard supervisory and control systems. The proposed SCADA system was developed using C++ language, targeted to x86-64/Windows 7 processing platforms, and is based on multithreading programming. The resulting system has a low implementation cost. The hardware architecture, along with the adopted software tools, satisfactorily meets all the requirements originally planned for the proposed system.

Research paper thumbnail of Synchronization method for synchronous generator based on UPFC

2013 IEEE Grenoble Conference, 2013

ABSTRACT This paper presents a technique for synchronizing synchronous generators without speed c... more ABSTRACT This paper presents a technique for synchronizing synchronous generators without speed control. The proposed construction is under development in a research project which aims to control auxiliary synchronous generators in a hydroelectric power unit. An UPFC device is used to achieve the synchronism of the synchronous generator with the power system. Simulation with different phases angles and voltage magnitude are presented to demonstrate the effectiveness and robustness of the proposed technique.

Research paper thumbnail of Architecture of a distributed system for acquiring knowledge in supporting decision making in operation/maintenance of electric power plants

2012 Sixth IEEE/PES Transmission and Distribution: Latin America Conference and Exposition (T&D-LA), 2012

This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes thro... more This paper presents a new approach to acquire a knowledge base (MKB) of continuous processes through a distributed system. The proposed methodology combines MKB and case-based reasoning (CBR) for adaptive knowledge base creation, maintenance and updating trough the use of an architecture with the following aspects: i) distributed architecture network; ii) real-time operation; iii) advanced visual interface. Although originally developed for use in hydroelectric power plants it is useful for other industrial processes in mission-critical with high cost of interruption. This work presents the system requirements, the aspects of the case base formation, the CBR cycle and the believe network.

Research paper thumbnail of Cartas De Smith Digitais Para a Aprendizagem Do Projeto De Osciladores e Amplificadores De Micro-Ondas

Proceedings of the L Brasilian Congress of Engineering Education

Research paper thumbnail of Aquametria por microondas : desenvolvimento de transdutor em microfita

Este trabalho apresenta uma metodologia para o desenvolvimento de transdutor de microondas para a... more Este trabalho apresenta uma metodologia para o desenvolvimento de transdutor de microondas para a mensuração de umidade em produtos agrícolas com a utilização de estruturas planares em microfita. O termo aquametria é definido na literatura como a área da instrumentação responsável por mensurar a quantidade de água presente em sólidos e líquidos via identificação de suas propriedades dielétricas. São apresentados alguns aspectos relativos à aquametria, seguidos do modelo matemático e numérico da interação das ondas eletromagnéticas no meio dielétrico com perdas. O modelo matemático é então especializado para dar conta de uma microfita com uma amostra úmida superposta. A partir desses resultados, são apresentadas três propostas de transdutores que buscam mensurar a permissividade dielétrica complexa efetiva do conjunto microfita mais amostra. Os transdutores propostos são então simulados com a aplicação do método de diferenças finitas no domínio tempo, objetivando não só verificar a q...

Research paper thumbnail of Instrumented Synchronous Feedback Workbench, Learning Object for the Electrical Machines Laboratory

2020 IEEE Global Engineering Education Conference (EDUCON), 2020

Seeking to meet the significant learning needs in the electrical machine laboratory, a workbench ... more Seeking to meet the significant learning needs in the electrical machine laboratory, a workbench with two small synchronous machines (low cost BLDC – Brushless Direct Current motors) is developed. They are mechanically and electrically coupled. Such a configuration is known as synchronous feedback or back-to-back load testing. A metalworking rotary table varies the mechanical power angle (torque angle) between machines. A real time SCADA – Supervisory Control and Data Acquisition, monitors the speed of rotation, voltages and currents in the time domain, the voltage and current phasors and acts on the machines drive. The power angle is calculated from the phasor diagram. The student interacts with the equipment by setting it in motion, accelerating the machines, and varying the mechanical angle through the rotary table. It can then differentiate the operation of machines such as generator and motor, the variation in load caused by the power angle between them, the synchronism, the power factor and the power angle. Progressively, and starting from the student’s action on the object of study, all concepts related to synchronous machines are learned. The workbench is low cost and uses safe voltages for risk free operation.

Research paper thumbnail of A Bayesian network to model a universe of possible drives of residential electrical loads

2018 Simposio Brasileiro de Sistemas Eletricos (SBSE), 2018

In electric power generation and distribution systems, three structures are capable of impacting ... more In electric power generation and distribution systems, three structures are capable of impacting energy quality: generation, distribution and loads. Currently, the diversity of the latter ranges from purely resistive loads such as heating systems to extremely nonlinear loads such as switched electronic power supplies. This has dramatically affected the quality of electric energy. The operation of these loads contributes to the reduction of the power factor of the installation, the injection of harmonic currents in the electrical network and the imbalance of currents and voltages between the phases in the case of three-phase systems. The implementation of a method capable of recognizing electrical loads and identifying them through algorithms can be used to manage the electric energy consumption, contributing a lot to the improvement of the quality of electric energy. In order to deal with uncertainty in the identification of these loads, probability distributions will be applied, wh...

Research paper thumbnail of Specific absorption rate (SAR) in the head of Google glasses and Bluetooth user's

2014 IEEE Latin-America Conference on Communications (LATINCOM), 2014

Two popular wireless communication devices are considered in this paper. Firstly, the Bluetooth w... more Two popular wireless communication devices are considered in this paper. Firstly, the Bluetooth which is one of the most popular mobile accessories and the Google glasses which are a representation of the new futuristic vision. It is well known that the absorption of electromagnetic waves on the human head for a certain period of time may lead to health problems such as headaches, or even worse, brain cancer. The Specific Absorption Rate (SAR) is simulated for three different head models and compared with the available international recommendations. The first model used is the Specific Anthropomorphic Mannequin (SAM phantom), as well as two realistic models of human head (i.e., a 34 years old adult and a 10 years old child). The simulations were performed using the finite difference time domain (FDTD) method and the frequency used to feed the antennas was 2.45 GHz.

Research paper thumbnail of Aquametria por micro-ondas

A medida do teor de umidade de materiais resulta em ganhos econômicos e ambientais ao possibilita... more A medida do teor de umidade de materiais resulta em ganhos econômicos e ambientais ao possibilitar o controle preciso da secagem de produtos agrícolas, de processos de cura e armazenagem, e reduzir perdas de material e consumo de energia. Tal medida pode ser feita através da interação de ondas eletromagnéticas nas frequências de micro-ondas. Apresenta-se o desenvolvimento histórico e o estado da arte dessa área da metrologia que é conhecida por aquametria por micro-ondas. Detalha-se o comportamento das ondas eletromagnéticas em dielétricos, o modelo de espalhamento nas interfaces das amostras, a relação entre a permissividade complexa e a umidade, métodos para a determinação da permissividade, instrumentos, sistemas e aspectos metrológicos da cadeia de medição para espectroscopia dielétrica. Dois novos métodos, com equações explícitas originais para a determinação da permissividade são obtidos. As novas equações resultam em incerteza menor que os métodos clássicos. Uma nova metodologia, através do método de Monte Carlo, é empregada para a avaliação das mesmas. Conclui-se que o desenvolvimento da aquametria passa, necessariamente, pelo aperfeiçoamento dos instrumentos e métodos para determinação da permissividade dos materiais.The measurement of moisture content of materials results in economic and environmental gains. Monitoring drying and curing of materials prevents loss of products and waste of energy. This can be done through the interaction of electromagnetic waves at microwave frequencies. This dissertation presents the historical development and the state-of-the-art in aquametry, the behavior of electromagnetic waves in dielectrics, sample interface scattering model, the relationship between the complex permittivity and moisture, methods for determining permittivity, instruments and metrological aspects of the measurement chain, and some instruments for dielectric spectroscopy. Two new methods, capable of providing explicit equation for the permittivity, are obtained and the Monte Carlo method is applied to determine their uncertainty. The new equations have lower uncertainty than the classic methods. The general conclusion is that the development of instrumentation and techniques in aquametry must be based in improvements in permittivity measurement

Research paper thumbnail of Non-resonant Permittivity Measurement Methods

Journal of Microwaves, Optoelectronics and Electromagnetic Applications, 2017

The measurement of the dielectric properties of materials has been applied in non-destructive tes... more The measurement of the dielectric properties of materials has been applied in non-destructive tests, humidity measurement, soil analysis and even cancer detection. The methods have been developed for over 70 years based on the interaction of the electromagnetic waves with the material under test. This work presents a general model of scattering parameters for non-resonant methods of transmission/reflection and single-port reflection. Equations for determining permittivity are obtained. New equations for short-circuited load and coupled load in the double reflection method are presented.

Research paper thumbnail of Synchronizing microgrids to the utility through a series compensator

2014 Power Systems Computation Conference, 2014

This paper presents a novel approach to deal with the synchronization of microgrids to the main g... more This paper presents a novel approach to deal with the synchronization of microgrids to the main grid. It is based on the use of a power electronic device derived from the original concept of the SSSC (Static Synchronous Series Compensator). The proposed scheme considers the connection of this device at the point-of-interconnection (POI) of the microgrid to the low voltage side of the substation transformer (main grid). The voltage originated by the series compensator is fully controlled in both amplitude and phase angle ensuring the conditions for the synchronization. The proposed scheme allows a smooth transition between the islanded operation and the grid connected operation overcoming typical problems observed when conventional methods are applied. Numerical results obtained for a hypothetical microgrid show the effectiveness of the proposed approach.

Research paper thumbnail of An integrated end-use scada-oscillography system for power quality analysis in smart grids

2013 IEEE PES Conference on Innovative Smart Grid Technologies (ISGT Latin America), 2013

This paper presents an innovative system (hardware and software) that incorporates the main funct... more This paper presents an innovative system (hardware and software) that incorporates the main functions typically found alone in SCADA, oscillography and advanced metering infrastructure systems. The developed system maintains all the characteristics of a SCADA system, suitable for the operation of a distributed generation, while it incorporates oscillography features and power quality measurements. The functions of oscillography and power quality measurements are shared by both smart grid and distributed generation owner on a bilateral basis. The developed system has a low cost implementation.

Research paper thumbnail of A digital phase-locked-loop for synchronization of single-phase sources with the utility grid

2013 IEEE Grenoble Conference, 2013

ABSTRACT This paper presents an innovative digital phase-locked-loop (PLL) implementation that us... more ABSTRACT This paper presents an innovative digital phase-locked-loop (PLL) implementation that uses a moving average filter with a very high rejection on the fundamental frequency and its harmonics. This PLL is very versatile and can be used for synchronizing single-phase sources, control of drives, among others. Due to its fully digital implementation it has a low cost, short settling time and high immunity to noise, disturbances and harmonic components. The method can be applied directly to microprocessor controllers connected in smart grids. Numerical results confirm the efficiency of the developed PLL.

Research paper thumbnail of Belief Network for Non-Intrusive Load Monitoring Methodology and Implementation

2019 IEEE PES Innovative Smart Grid Technologies Conference - Latin America (ISGT Latin America)

This paper proposes Non-Intrusive Load Monitoring (NILM) technique using Bayesian networks to ide... more This paper proposes Non-Intrusive Load Monitoring (NILM) technique using Bayesian networks to identify which load turn-on in certain condition. Explain how to find the values for the conditional probability tables (CPT’s) and presents a methodology to implement the network structure. The information used in the inference are defined as Boolean variables, related with well-defined thresholds, to then be used in Monte Carlo Markov Chain (MCMC) to infer its probabilities. An interface in LabView was developed to question the system, including the MCMC implementation. The measures and characteristics to identify each specific load are shown, and also the advantages of using changeable thresholds.