Helder de Paula

Helder de Paula
Federal University of Uberlândia | UFU · Faculty of Electrical Engineering (FEELT)

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53
Publications
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150
Citations

Publications

Publications (53)
Article
Especially in the mining industry, Pulse Width Modulated Voltage Source Converters (PWM-VSC) are commonly used to drive induction motors at long distances from the inverter. However, this can cause unwanted high-frequency phenomena due to the long cables used for the converter-to-motor connection. A new configuration has been proposed to address th...
Article
Full-text available
Across various productive sectors, failures in electric motors can lead to financial losses, poor production quality, and accidents. Even though motors in high-performance/precision applications are controlled in a closed loop, this category of drive is the least explored in the literature when the subject falls on the detection of inter-turn stato...
Article
This work presents a study on the use of electrostatic shields to reduce bearing currents (both Electrostatic discharge machining and circulating currents), focusing on its thermal impact on the motor operation. 2-D finite element models are utilized to analyze the temperature distribution inside the coil winding slot of motors both with and withou...
Article
In a previous work, the authors addressed electrostatic shielding to reduce the bearing discharge currents (Electrostatic discharge machining currents - EDM). In order to expand the application of such a shielding device, this paper presents an analysis of its use to reduce the inverter-induced circulating bearing currents on induction machines. Em...
Conference Paper
This paper presents a compilation of the dielectric failure mechanisms of medium and high voltage cables. As well as, the various diagnostic methods found in the literature and used in the field, highlighting their advantages and limitations. The methods that use partial discharges to evaluate the insulation condition are emphasized and the main an...
Conference Paper
The expansion of offshore wind farms, the need for oil production in increasingly deeper waters and the demand for larger power transmission systems have required new levels of technology and performance of submarine power cables. The long length of these cables makes such applications more susceptible to a series of undesirable electromagnetic phe...
Article
Especially in the mining industry, pulsewidth modulation voltage source converters driving induction motors located far away are often present. In this case, due to the long cable used for the converter-to-motor connection, several unwanted high-frequency phenomena are generated. In this context, a new configuration for motor drive systems was prop...
Article
In the last three decades, the study of inverter-induced bearing currents has become a very important line of research, and hundreds of works related to this theme can be found in the literature. Thus, several contributions concerning these currents were made, such as in the areas of modeling and simulation techniques, selection of appropriate miti...
Article
High-frequency phenomena require appropriate models to be accurately reproduced and analyzed by means of computational simulations. Within industrial facilities, insulated cables are widespread and their modeling in a broad range of frequencies is complex due to the proximity between these and particular issues concerning the installation methods....
Article
Full-text available
Partial discharge (PD) investigations can identify and localise incipient failures in power transformers early, thus avoiding considerable financial losses. The feature extraction of PD signals is a fundamental step for the development of such location techniques since it directly influences the performance of a location method. This study presents...
Conference Paper
Em certas aplicações industriais críticas, as respectivas cargas são acionadas por motores de indução controlados em malha fechada. No entanto, esta categoria de acionamento é a menos explorada na literatura no que se refere à detecção de falhas. Isto ocorre porque a estrutura do controle em malha fechada modifica drasticamente, ou mesmo oculta, as...
Conference Paper
O grande desafio para empresas e concessionárias que possuem redes elétricas subterrâneas é identificar os cabos que estão em boas condições de operação, os que demandam manutenção e aqueles que precisarão ser substituídos em um curto intervalo de tempo, para que se torne possível realizar um planejamento adequado dos investimentos e das intervençõ...
Conference Paper
Este trabalho apresenta uma ampla e minuciosa revisão bibliográfica sobre a avaliação de descargas parciais para o diagnóstico e monitoramento do estado da isolação de cabos de média e alta tensão. Todos os possíveis métodos de detecção da atividade de descargas parciais, com os respectivos sensores adequados para cada situação, são discutidos de f...
Conference Paper
Nesse artigo, uma técnica de modulação vetorial utilizada para mitigar a tensão de modo comum em conversores matriciais, baseada na substituição dos vetores nulos pelos rotativos, é avaliada sob outros aspectos, tais como a severidade das sobretensões transitórias que podem surgir nos terminais do motor. Este fenômeno se manifesta ao se utilizar ca...
Conference Paper
Os motores elétricos de média tensão que acionam ventiladores industriais são grandes consumidores de energia elétrica. A vazão deste tipo de sistema de ventilação é geralmente controlada por válvulas do tipo damper, alocadas no lado de sucção dos ventiladores. Nessas condições, ainda que com vazão reduzida no sistema, a demanda de energia por part...
Conference Paper
Este trabalho apresenta uma ampla discussão sobre os testes mais relevantes, on-line e off-line, empregados em âmbito industrial para o desenvolvimento da manutenção preditiva de motores de indução trifásicos (MITs). A definição de procedimentos apropriados, focados em prognóstico de falhas, é de vital importância para o programa de manutenção da e...
Article
Full-text available
The authors deal with the use of electrostatic shielding to mitigate the electric discharge machining (EDM) currents on the induction machine bearings. Employing 2D and 3D models, several finite element analysis (FEA) simulations were thoroughly made addressing the shielding effectiveness to attenuate the shaft‐to‐frame voltage and the associated e...
Article
Full-text available
This paper presents a new concept in underground medium voltage substations for an optimized operation performance and overall cost reduction. Due to its high-level embedded automation and communication systems, increased standards of reliability, availability and security are reached. Moreover, less expensive IP00 equipment can be used instead of...
Article
The early identification and location of high-frequency current pulses related to partial discharges (PDs) in the solid insulation of power transformers enable the optimization and planning of maintenance interventions, preventing unexpected power interruptions and reducing downtime. Even though several techniques for PD signal experimental generat...
Article
Cable models for high-frequency studies require the calculation of per-unit-length parameters in a wide frequency range. Analytical methods, such as the ones implemented in traditional electromagnetic transient simulators, are frequently used for this purpose. However, they are accurate only for systems in which the cables are sufficiently apart fr...
Article
The paper presents an experimental investiga-tion on the efficiency of different underground transmis-sion/distribution line magnetic shielding techniques. Measure-ment results of magnetic field and temperature rise around the cable conductors are shown. An analysis of the thermal effects of each shielding technique on the line power capacity is pr...
Article
High-frequency problems related to PWM motor drive systems with long cables are widely discussed in the literature and are very harmful to the system components, resulting in motor insulation failures, bearing damage and electromagnetic interference, among others. As a solution, it was proposed in a previous work an alternative system configuration...
Article
Full-text available
There are important concerns about the problems caused by high values of low-frequency magnetic field in urban centers. Two of them have received particular attention: the electromagnetic interference in sensitive equipment and the potential adverse health effects on human beings. In this way, many solutions to mitigate the magnetic field generated...
Article
Full-text available
This paper presents a strategy for protecting high power IGCT-based converters which are currently used in a wide range of drive applications. The protection of such converters against internal faults has been addressed in the technical literature, but the main focus has been on the solutions to disconnect the converter from the mains. In this pape...
Article
Resumo -Este artigo trata da análise dos impactos devido às descargas atmosféricas em Estações de Transmissão e Distribuição (ETD's) de 88 kV/13,8 kV e nas linhas de Subtransmissão e de Distribuição que se conectam a estas ETD's. De uma maneira geral, visando fazer a proteção de ETD's contra sobretensões oriundas de descargas atmosféricas em ramais...

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