Papers by Josemir Coelho Santos
Development of a digital optical Instrument Transformer with process bus interface according to IEC 61850-9-2 standard
2015 IEEE PES Innovative Smart Grid Technologies Latin America (ISGT LATAM)
This article presents a prototype development of a digital optical Instrument Transformer with IE... more This article presents a prototype development of a digital optical Instrument Transformer with IEC 61850-9-2 interface. We present the main topics related to the implementation of a process bus according with IEC 61850-9 standard and a block diagram of Instrument Transformer prototype proposed. Some results from mathematical simulations and prototype testing are presented at the end of this article.
Polyimide removal, cleaving, and fusion splicing of cylindrical and square fused silica capillaries for new separation and detection layouts in capillary electrophoresis and chromatography
Journal of Separation Science
Fusion splicing is an already mature technology used to join the ends of optical fibers in the te... more Fusion splicing is an already mature technology used to join the ends of optical fibers in the telecommunication industry. However, there is a lack of reliable and well‐described protocols to join the ends of fused silica microtubes or capillaries using fusion splicing. In this work, a step‐by‐step procedure is proposed and demonstrated to find the optimal operation conditions to splice the ends of fused silica capillaries by fusion. The two most appropriate and known technologies were tested and optimized: the microfurnace technique (or hot filament technique) and the electric arc technique. It is shown that both produce good splices when the capillaries are well cleaved. For this reason, the removal of the external coating, which is important for good cleavage, was also revised. The cleaving techniques were also compared among themselves. As a result, fusion splices of cylindric‐to‐cylindric, cylindric‐to‐square, and square‐to‐square capillaries are demonstrated. They have potenti...
Sensors, 2020
Dissolved gas analysis (DGA) is one of the most important methods to analyze fault in power trans... more Dissolved gas analysis (DGA) is one of the most important methods to analyze fault in power transformers. In general, DGA is applied in monitoring systems based upon an autoregressive model; the current value of a time series is regressed on past values of the same series, as well as present and past values of some exogenous variables. The main difficulty is to decide the order of the autoregressive model; this means determining the number of past values to be used. This study proposes a wavelet-like transform to optimize the order of the variables in a nonlinear autoregressive neural network to predict the in oil dissolved gas concentration (DGC) from sensor data. Daubechies wavelets of different lengths are used to create representations with different time delays of ten DGC, which are then subjected to a procedure based on principal components analysis (PCA) and Pearson’s correlation to find out the order of an autoregressive model. The representations with optimal time delays fo...
Energies, 2018
Transformers are one of the most important part in a power system and, especially in key-faciliti... more Transformers are one of the most important part in a power system and, especially in key-facilities, they should be closely and continuously monitored. In this context, methods based on the dissolved gas ratios allow to associate values of gas concentrations with the occurrence of some faults, such as partial discharges and thermal faults. So, an accurate prediction of oil-dissolved gas concentrations is a valuable tool to monitor the transformer condition and to develop a fault diagnosis system. This study proposes a nonlinear autoregressive neural network model coupled with the discrete wavelet transform for predicting transformer oil-dissolved gas concentrations. The data fitting and accurate prediction ability of the proposed model is evaluated in a real world example, showing better results in relation to current prediction models and common time series techniques.
Challenges to the implementation of a real-time process bus according to IEC 61850-9
IEEE PES Innovative Smart Grid Technologies, Europe, 2014
This article presents a summary of the most significant information obtained by the authors for i... more This article presents a summary of the most significant information obtained by the authors for implementing a process bus according to IEC61850-9 Standard. The results of this study were grouped into five relevant topics: IEC61850-9 variations, process bus reliability, time synchronization between devices, cyber security and measurement accuracy. This research aims mainly to disseminate the information obtained, stimulate discussion about the main challenges for process bus implementation and build a theoretical basis for developing a communication interface that will be a component of an innovative prototype of a totally digital optical voltage transformer.
On-field instrument transformers calibration using optical current and voltage transformes
2014 IEEE International Workshop on Applied Measurements for Power Systems Proceedings (AMPS), 2014
This paper presents the development of a system based on optical current transformers (OCTs) and ... more This paper presents the development of a system based on optical current transformers (OCTs) and optical voltage transformers (OVTs) for on-field calibration of conventional instrument transformers (ITs), avoiding necessities of removing the equipment for laboratory environment and interruption of supply for on-field calibration procedures. To accomplish these aims it was required the development of suitable OVTs and OCTs with accuracy classes equal to or better than 0.03%, suitable for calibration of conventional ITs intended to supply measuring instruments (accuracy classes equal to 0.3%). It was also necessary to develop the appropriate methodology to perform expedite on-field calibration of conventional ITs without interruption of service. As a further result of project, the on-field calibrations results may provide to sponsor utility recommendations for its maintenance procedures, aimed at replacing the identified off-class ITs or allow the use of algorithms for errors/losses compensation to be implemented on measuring instruments, in case of such resource be available.
Modeling residual thermal stress-induced integrated optical waveguides on Bi<inf>12</inf>GeO<inf>20</inf> substrate for electrooptic modulation application
2009 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2009
The residual thermal stress study of an optical waveguide based on isotropic material (bismuth ge... more The residual thermal stress study of an optical waveguide based on isotropic material (bismuth germanate, BGO), the Pockels eletro-optic effect and the modal optical analyses were investigated for the optical modulation purpose. The analyses were performed by a full vector finite element based program. The optical propagation characteristics of the stress-induced waveguides and the main electro-optic parameters were evaluated considering
Redução no Tempo Médio de Atendimento a Ocorrências Emergenciais Aplicando o Sinalizador de Faltas
Resumo O objetivo deste trabalho é apresentar o potencial de redução no tempo médio de atendime... more Resumo O objetivo deste trabalho é apresentar o potencial de redução no tempo médio de atendimento a ocorrências emergenciais através da utilização do Sinalizador de Faltas, produto desenvolvido pela CPFL, em parceria com a Expertise Engenharia e a USP. Este equipamento agiliza a tarefa de localização de defeitos na rede de distribuição, indicando à equipe de manutenção o caminho até o ponto da falha. Com a redução do tempo de localização de defeitos diminui também o tempo médio de atendimento a ocorrências emergenciais, o que influencia positivamente os indicadores de qualidade de prestação de serviços das concessionárias distribuidoras definidos no PRODIST.
AIP Conference Proceedings, 2008
Linear accelerations measurements are needed in many applications, as industry, military, aircraf... more Linear accelerations measurements are needed in many applications, as industry, military, aircrafts, space navigation, robotics and others. Actually, the most usual solutions to measure linear accelerations are three piezoelectric sensors used in orthogonal mounting, or MEM's sensors chips. Angular accelerations also are interesting to control and stabilize structures, like satellites and servo motors. It is possible to measure angular accelerations in two ways: direct measurement (using special sensors), or indirect measurements (obtaining acceleration of the angular velocity information) . This work intends to present the structural and optical requirements of a six degree freedom opto-mechanical accelerometer based on fiber Bragg grating (FBG). With this sensor, it will be possible the direct measurement of three axial accelerations, and of three angular accelerations, with unlimited rotation angle, using one single proof mass. The FBG's are used as strain sensors and sustaining elements of the proof mass in the structure. Simulations have demonstrated that cross influences of 10 parts per million at worst case are possible. This kind of accelerometer may be used in navigation control, structural monitoring, satellite stabilization, guidance control and harsh environments, for example. The project requirements include the wavelength of FBG's, pre-strain and length of active segment of optical fibers, dimensions, material and structure of inertial proof mass and position of the fibers in the sustaining structure
A Modified Algorithm for Compressed Sensing Multispectral Image Recovering using a Single Pixel Camera
OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES), 2021
The present article shows a modified compressed sensing algorithm using the underlined physical c... more The present article shows a modified compressed sensing algorithm using the underlined physical configuration of Digital Micromirror Device- DMD - a matrix - to recover, successfully, images with a Single Pixel Cam simulation apparatus.
Construção de acoplador óptico (3dB) para sistemas a fibra óptica plástica (POF)
9 SIICUSP; XVII CICTE: resumos, 2001
Sensors (Basel, Switzerland), 2020
The prediction of partial discharges in hydrogenerators depends on data collected by sensors and ... more The prediction of partial discharges in hydrogenerators depends on data collected by sensors and prediction models based on artificial intelligence. However, forecasting models are trained with a set of historical data that is not automatically updated due to the high cost to collect sensors’ data and insufficient real-time data analysis. This article proposes a method to update the forecasting model, aiming to improve its accuracy. The method is based on a distributed data platform with the lambda architecture, which combines real-time and batch processing techniques. The results show that the proposed system enables real-time updates to be made to the forecasting model, allowing partial discharge forecasts to be improved with each update with increasing accuracy.
Modeling of magnetostrictive optical modulator for application as a magnetic field sensor
2017 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC), 2017
The work presents a new proposition of an integrated optical device applicable as optical magneto... more The work presents a new proposition of an integrated optical device applicable as optical magnetometer. The studies of an optical waveguide formed by thermally induced static stress (ISS) and modulation achieved by magnetostriction of a TbCo2 thin film over Bismuth Germanate (BGO) are shown. The magnetooptical effect and the modal optical analyses were investigated for the optical modulation purpose. The analyses were performed by simulation software based on Finite Elements Method (FEM). The optical propagation characteristics of the magnetooptically disturbed guided mode in stress-induced waveguide were evaluated indicating the viability of proposed device application as magnetometer.
Demodulação Coerente do Sinal de Saída de Transformador de Potencial Óptico
This work addresses a technique of coherent demodulation based on the synchronous detection of pe... more This work addresses a technique of coherent demodulation based on the synchronous detection of peak and valley values of the photocurrent produced by a photodiode connected through an optical fiber to the output of a recover interferometer, which is part of an Optical Voltage Transformer (OVT). The adopted OVT topology allows the recover interferometer output signal to hold the relevant information about the ac high-voltage applied to a sensor interferometer. A series of tests was conducted to estimate the OVT performance, in a laboratory environment, measuring ac high-voltages up to 20kV. The good results obtained are very promising, and encourages to pursue this research aiming to develop an OVT prototype suitable for application in electrical distribution and transmission substations.
A Modified Algorithm for Compressed Sensing Multispectral Image Recovering using a Single Pixel Camera
OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES), 2021
The present article shows a modified compressed sensing algorithm using the underlined physical c... more The present article shows a modified compressed sensing algorithm using the underlined physical configuration of Digital Micromirror Device- DMD - a matrix - to recover, successfully, images with a Single Pixel Cam simulation apparatus.
Development of Transmissible Photopletysmography Prototype Sensor Using Polimeric Fiber Optic
AIP Conference Proceedings, 2008
This paper showed the development of a transmissible prototype sensor using polymer fiber optic, ... more This paper showed the development of a transmissible prototype sensor using polymer fiber optic, in order to verify that the optic fiber is capable to transmit the signal through the receptor device and thus use it to obtain the needed parameters in small biological areas. The sensor consists one plastic clip with silicon inside, one infrared (940 nmn) LED (Light
Capacitive and inductive sensors for diagnosing air-gap anomalies in synchronous generators
2015 IEEE International Electric Machines & Drives Conference (IEMDC), 2015
This paper presents the development of distance sensors to measure air-gap irregularities in sync... more This paper presents the development of distance sensors to measure air-gap irregularities in synchronous generators. Among various causes, air-gap anomalies may arise due to shaft eccentricity, which will be dealt with in this work. A prototype machine was specially manufactured allowing the deformation of rotor and stator yokes, as well as the radial displacement of its shaft position. These features permit assessment of the performance of the sensors under study. The developed sensors are of the capacitive and inductive types, placed in the wedges of the stator slot openings, and symmetrically distributed along the air-gap surface.
Development of distance sensors for diagnosing air-gap anomalies in synchronous generators
2015 IEEE 24th International Symposium on Industrial Electronics (ISIE), 2015
This paper presents the development of distance sensors to measure air-gap irregularities in sync... more This paper presents the development of distance sensors to measure air-gap irregularities in synchronous generators for diagnosing static eccentricities. Capacitive and inductive sensors were developed to measure the thickness of the air-gap between the stator and the rotor poles. In order to obtain an absolute measurement of distance, an optical fiber chromatic confocal sensor system is used as a reference for the other sensors by means of a local calibration procedure. It can be concluded that capacitive and inductive sensors developed show satisfactory and promising results of air-gap measurement.
Applicability of knowledge management practices at scientific research environment
2015 10th Iberian Conference on Information Systems and Technologies (CISTI), 2015
The Knowledge Management (KM) is becoming a valuable strategic resource for the life of individua... more The Knowledge Management (KM) is becoming a valuable strategic resource for the life of individuals and companies, and has been identified by scholars, researchers and scientists as relevant and required for the growth of organizations in various fields. This paper presents the results of a survey research with exploratory which seeks to identify what KM practices adopted by researchers in the research environment and to understand to what extent are contributing to scientific production. The results indicate that several KM practices are adopted in the research environment. However, it is observed that these are personal initiatives by researchers, without any coordination or management with specific purpose. This scenario shows that there must be a greater awareness of the importance of KM in the research environment. In this sense, an organizational culture should be noted that values knowledge not only as an essential device to researchers, but as a fundamental resource to research environments able to boost the production of scientific knowledge.
Aplicação De Modelo De Framework De Procedimentos Para Criação e Gestão Do Conhecimento Em Aplicações Web
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Papers by Josemir Coelho Santos