The diagnostic technique, polarization and depolarization current (PDC) is useful for insulation testing. It requires applying a DC step voltage to the test sample and measuring the current. To measure fast PDC phenomena a fast step is needed. One way of applying a fast high voltage step is to use power electronic switches. Series connection can be used to increase the voltage limit, but this result in unequal voltage sharing unless equipped with voltage balancing. In this work a high voltage vacuum reed switch is investigated as a simple and low-cost alternative to power electronic switches, handling up to 10 kV with a single device. The switch turn on and off behavior was studied. It was found that the initial turn-on is good, in the range of nanoseconds, but there is a problem with the vacuum recovering its insulating properties at low currents before the contacts fully close. The required output voltage level is therefore obtained only after a further settling time that increases with increased input voltage and is much longer than the initial breakdown, e.g. 20 µs for the case of 4.5 kV input voltage. Other limitations of the fast high voltage PDC were also studied. The output voltage was measured across the test sample without adding an intentional resistor in the circuit. There were large oscillations for 1 µs but these oscillations are damped due to inherent resistance of the connecting leads, series resistance of the capacitors and resistance of the reed switch. A comparison is made between the measured and the simulated results using MATLAB to see the effect of parasitic inductance. A damping resistor was added in the circuit and the output results were again compared. With the addition of the damping resistor, the number of oscillations were reduced and their time scale was limited to 0.1 µs . An analysis is made at the end which describes the limitation occurring in determining the high frequency component of PDC. The current during the step is many orders of magnitude higher than the polarization current even at 1 µs , so measurement of the current and protection of the apparatus is not trivial.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-12-12T13:10:44Z No. of bitstreams: 1 Felipe de Carli_.pdf: 6857644 bytes, checksum: 51df2faf2ff2365c2443afa4f23a4292 (MD5) / Made available in DSpace on 2018-12-12T13:10:44Z (GMT). No. of bitstreams: 1 Felipe de Carli_.pdf: 6857644 bytes, checksum: 51df2faf2ff2365c2443afa4f23a4292 (MD5) Previous issue date: 2018-10-26 / FATEC – Fundação de Apoio á Tecnologia e Ciência / A geração, transmissão e distribuição de energia elétrica têm papel chave no desenvolvimento econômico de um país. A qualidade e disponibilidade da energia elétrica relacionada a distribuição tem impacto direto na economia e na qualidade de vida das pessoas. Conceitos de Redes de Distribuição Inteligentes tem ganhado cada vez mais força com o intuito de melhorar a qualidade dos serviços prestados. A tensão em regime permanente é um dos principais parâmetros de qualidade de energia elétrica em redes de distribuição e muitas vezes o seu controle requer soluções de elevada complexidade e investimento. Tensões fora de especificação tem impactos negativos para os consumidores finais, uma vez que, podem gerar danos aos equipamentos, interrupção em serviços fundamentais, e inconvenientes para a sociedade. Desta forma, o presente trabalho busca desenvolver um protótipo de controle inteligente e dinâmico aplicado para reguladores de tensão de distribuição com a capacidade de coletar informações do perfil de consumo do alimentador, realizar o auto ajuste de seus parâmetros e enviar informações para o sistema de supervisão. O protótipo dividido em um módulo de controle e módulo fuzzy que foi desenvolvido em escala de laboratório. Baseado no carregamento do alimentador, o dispositivo é capaz de calcular os parâmetros básicos de auto-ajuste, ou seja, a temporização, faixa de insensibilidade e compensações de queda na linha. Os resultados globais desse trabalho mostram que o desenvolvimento de um controle dinâmico e inteligente para reguladores de tensão é viável e pode ser aplicado em redes de distribuição reais. O cálculo dos parâmetros de temporização, tensão de referência, compensação de queda na linha melhora o perfil de tensão de uma rede de distribuição, pois minimiza as oscilações de tensão em baixa e alto carregamento da linha, conforme testes realizados com dados de um alimentador real. Entende-se que os resultados globais deste trabalho servem de fundamento para um estudo técnico-econômico de ampliação desta estrutura de controle para outros reguladores de tensão de redes de distribuição. / The electricity generation, transmission, and distribution play a role key in the economic development of a country. The quality and availability of electricity related to distribution has a direct impact on the economy and people's quality of life. Concepts of smart grids has gained more strength in order to improve the quality of services provided. Steady-state voltage is one of the main quality parameters of electrical power in distribution grids and often its control requires solutions of high complexity and investment. Out-of-specification voltage have negative impacts on end-users, as it can cause damage to equipment, outage in key services, and inconvenience to community. In this way, the present work seeks to develop a prototype of intelligent and dynamic control applied to distribution voltage regulators with the ability to collect information of the feeder consumption profile, perform the self-tuning of its parameters and send information to supervisory system. The prototype divided into a control and fuzzy modules was developed on a laboratory scale. Based on loader readings, the device is able to calculate the basic parameters of self-adjustment, ie time delay, dead band and line drop compensation. The overall results of this work show that the development of a dynamic and smart control for step voltage regulators is feasible and can be applied in real distribution grid. The calculation of the time delay, reference voltage, line drop compensation improves the voltage profile of a distribution grid, as it minimizes voltage variations at low and high line loading, according to tests performed with data from a real feeder. It is understood that the overall results of this work serve as a basis for a technical-economic study to extend this control structure to other step voltage regulators in distribution grids.

This master's thesis deals with the measurement of grounding systems in HV/LV distribution networks, which includes grounding system of distribution substation and transmission lines. Explores the issue and principles for the measurement of parameters, which are important for the protection of persons and animals in order not to touch exposed conductive part accidentally, protection of electrical machines and equipment against high fault current and dangerous surges while the correct function of the connected electrical equipment is maintained. These parameters include earth potential rise, ground resistance, soil resistivity, touch voltage, step voltage and transferred potential to the LV network. The aim of this work is the preparation, analysis and subsequent evaluation for the real measurement in practice. These earthing-system measurements were carried out at the distribution station and the concrete pole with a section disconnector. Then a numerical model of the grounding system of concrete pole was created in ANSYS. Subsequent evaluation of the results as numerical terms (comparison measurements and simulated results) and evaluation in terms of analytical (measurement results compliance with the standard) including the numerical model of the earthing system is solved in the practical part of the master's thesis.

Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2018-02-19T16:48:56Z No. of bitstreams: 1 CAMILA MADEIROS ALCANTARA PIMENTA.pdf: 4765494 bytes, checksum: dac59f354329911b1dfcb8422a61af1b (MD5) / Made available in DSpace on 2018-02-19T16:48:56Z (GMT). No. of bitstreams: 1 CAMILA MADEIROS ALCANTARA PIMENTA.pdf: 4765494 bytes, checksum: dac59f354329911b1dfcb8422a61af1b (MD5) Previous issue date: 2017-12-15 / Electrical grounding is part of the Atmospheric Discharge Protection System (ADPS), whose functions are to provide a path for the circulation of electric current in the ground and to enable the detection of a possible fault between the energized conductors and the earth. For grounding to be efficient, some characteristics must be taken into account, such as soil type and resistivity. In this sense, measurements of resistivity and soil stratification are important for a correct sizing of the grounding system. Soils with high water concentration (low resistivity) are better current conductors than dry soils, for example. Soils with high resistivity can cause a return current. Thus, some decisions aimed at strengthening the grounding system should be taken when there are soils with inadequate grounding characteristics. Therefore, this work aims to evaluate the influence of soil electrical resistivity and enveloping types using concrete types in the substation electrical grounding system through software simulations, taking into account soil resistivity characteristics. In the analysis of types of envelopment, it was possible to observe that the concretes with greater amount of water in their composition have a lower electrical resistivity. The use of concrete enveloping is feasible for soils with high resistivity, as in the case of the land located in the city of Campinas, and it was possible to verify that for soils with low resistivity its use may be impractical since other options such as inclusion of more cables and installation of the rods in the layers with less resistivity are sufficient and more economical. / O aterramento el?trico faz parte do Sistema de Prote??o Contra Descargas Atmosf?ricas (SPDA), cujas fun??es s?o fornecer um caminho para a circula??o de corrente el?trica na terra, escoamento para a terra de cargas induzidas nas carca?as dos equipamentos el?tricos e, em conjunto com os dispositivos diferenciais-residuais, possibilitar a detec??o de uma poss?vel falha entre os condutores energizados e a terra. Para que o aterramento seja eficiente, algumas caracter?sticas devem ser levadas em considera??o, tais como o tipo e a resistividade do solo. Neste sentido, medi??es da resistividade e a estratifica??o do solo s?o importantes para um dimensionamento correto do sistema de aterramento. Solos com alta concentra??o de ?gua (baixa resistividade) s?o melhores condutores de corrente do que um solo seco, por exemplo. Solos com alta resistividade podem ocasionar uma corrente de retorno. Assim, algumas decis?es visando o refor?o do sistema de aterramento devem ser tomadas quando se tem solos com caracter?sticas inadequadas ao aterramento. Portanto, esse trabalho teve como objetivo avaliar a influ?ncia da resistividade el?trica do solo e de tipos de envelopamento utilizando tipos de concreto no sistema de aterramento el?trico de subesta??es atrav?s de simula??es em software, levando em conta as caracter?sticas de resistividade do solo. Nas an?lises de tipos de envelopamento, foi poss?vel observar que os concretos com maior quantidade de ?gua em sua composi??o possuem uma resistividade el?trica mais baixa. A utiliza??o do envelopamento de concreto ? vi?vel para solos com alta resistividade, como ? o caso do terreno localizado na cidade de Campinas, e foi poss?vel verificar que para solos com resistividade baixa sua utiliza??o pode ser invi?vel j? que outras op??es como inclus?o de mais cabos e instala??o das hastes nas camadas com menor resistividade s?o suficientes e mais econ?micas.