Dissertations / Theses on the topic 'High voltage electric field'
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Bas, Gokcen. "Electric Field Analysis In Stress Controlled High Voltage Cables." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605778/index.pdf.
Okubo, H., T. Otsuka, K. Kato, N. Hayakawa, and M. Hikita. "Electric field optimization of high voltage electrode based on neural network." IEEE, 1997. http://hdl.handle.net/2237/6881.
Mesgarpour, Tousi Maryam. "Electric Field Grading and Electrical Insulation Design for High Voltage, High Power Density Wide Bandgap Power Modules." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100621.
Doctor of Philosophy
In power engineering, power conversion term means converting electric energy from one form to another such as converting between AC and DC, changing the magnitude or frequency of AC or DC voltage or current, or some combination of these. The main components of a power electronic conversion system are power semiconductor devices acted as switches. A power module provides the physical containment and package for several power semiconductor devices. There is a trend towards the manufacturing of electrification apparatuses with higher power density, which means handling higher power per unit volume, leading to less weight and size of apparatuses for a given power. This is the case for power modules as well. Conventional "silicon (Si)-based semiconductor technology" cannot handle the power levels and switching frequencies required by "next-generation" utility applications. In this regard, "wide bandgap (WBG) semiconductor materials", such as "silicon carbide (SiC)"," gallium nitride (GaN)", and, soon, "gallium oxide" and "diamond" are capable of higher switching frequencies and higher voltages, while providing for lower switching losses, better thermal conductivities, and the ability to withstand higher operating temperatures. Regarding the high power density concept mentioned above, the challenge here, now and in the future, is to design compact WBG-based modules. To this end, the extremely nonuniform high electric field stress within the power module caused by the aforementioned trend and emerging WBG semiconductor switches should be graded and mitigated to prevent partial discharges that can eventually lead to breakdown of the module. In this Ph.D. work, new electric field grading methods including various geometrical techniques combined with applying nonlinear field-dependent conductivity (FDC) materials to high field regions are introduced and developed through simulation results obtained from the models developed in this thesis.
Loza, Emmanuel. "CASCADED HIGH VOLTAGE CONVERTER WITH VARIABLE CONTROL FOR PULSED ELECTRIC FIELD APPLICATIONS." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/807.
Que, Weiguo. "Electric Field and Voltage Distributions along Non-ceramic Insulators." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1037387155.
Fylladitakis, Emmanouil D. "Characterisation of electrohydrodynamic fluid accelerators comprising highly asymmetric high voltage electrode geometries." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/13670.
Zhou, Churui. "Space charge dynamics in polyethylene under periodical high voltage electric fields." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/418005/.
Bloom, Matthew Anthony. "DC, RF, and Thermal Characterization of High Electric Field Induced Degradation Mechanisms in GaN-on-Si High Electron Mobility Transistors." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/966.
Fatokun, Folasade Okedoyin. "Corona ions from high voltage powerlines : production, effect on ambient particles, DC electric field and implications on human exposure studies." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/20714/1/Folasade_Fatokun_Thesis.pdf.
Fatokun, Folasade Okedoyin. "Corona ions from high voltage powerlines : production, effect on ambient particles, DC electric field and implications on human exposure studies." Queensland University of Technology, 2008. http://eprints.qut.edu.au/20714/.
Michelarakis, Michail. "Electric field distribution of sphere-plane gaps : A SIMULATION APPROACH." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187651.
Ökningen av spänningsnivåerna i kraftöverföringssystem har lett till högre kop-plingstransienter under drift. Konstruktionen av utrustning och nätverkskomponen-ter som kan motstå en sådan påkänning, kräver en noggrann förstudie av de elektriska fältet som genereras av dessa transienter. Ett gap av sfär-platta är den mest teoretiskt och praktiskt intressanta elektrodkon-figurationen att studera. Hittills har majoritetet av genomfört arbete avsett att studera urladdningsegenskaper för denna struktur. Dock krävs studie av elektrostatiska elek-triska fältet. En noggrann beräkning av elektriska fältet kan bidra till en ännu bättre förståelse för urladdningsegenskaper och principerna bakom dem. I detta projekt presenteras en simuleringsmetod för beräkning av elektrostatiska fäl-tet av en sfär-plan konfiguration, med varierande dimensioner av sfären och gapavstån-det. För detta ändamål har använts en Finite Element Method (FEM) lösning, där kon-figurationen utformades och problemets numeriska lösningen genomfördes. Därefter har gjorts ett försök för att ange genombrottsspänningen baserad på beräkning och distribution av elektriskta fältet. Resultat registrerades från både simulering av elektrostatiska modellen och beräkn-ing av genomslagsspänningen. Ett av de viktigaste resultaten var specifikationen av ett ungefärligt förhållande mellan diametrarna av sfären och röret där sfären är monterad. Som en konsekvens blev studiet av elektriska fältfördelningen lättare, medan en exakt beräkning av genomslagsspänningen uppnåddes. En valideringsserie har genomförts genom jämförelse med de redan existerande, publicerade och opublicerade, experimentella tester och ett antal slutsatser har noterats. En av de mest meningsfulla, var specifikation av sambandet mellan den elektrostatiska modellen och provmätningarna samt hur dessa olika tillvägagångssätt kan kopplas till varandra på ett praktiskt och effektivt sätt. Slutligen finns det ett förslag för fortsatta arbete samt eventuella förbättringar av redan genomfört arbete.
Jin, Donghyun. "Dynamic ON-resistance in high voltage GaN field-effect-transistors." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91108.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Recently, the development of energy efficient electrical power management systems has received considerable interest due to its potential to realize significant energy savings for the world. With current Si-based power electronics system being matured, GaN Field-Effect-Transistors have emerged as a disruptive technology with great potential that arises from the outstanding material properties of GaN. However, in spite of great progress in GaN device fabrication, electrical reliability and a number of unique anomalies of GaN remain key challenges that prevent the wide deployment of this technology. In particular, the dynamic ON-resistance (RON), in which the RON of the transistor remains high for a certain period of time after a high-voltage OFF-ON switching event, is a critical concern. This phenomenon greatly affects the efficiency of electrical power management circuits based on GaN power transistors. This thesis investigates in depth this important issue. Firstly, we have developed a new dynamic RON measurement methodology which can observe dynamic RON transients after OFF-to-ON switching events over many decades in time. We have experimentally demonstrated this technique on GaN-on-SiC high-voltage HEMTs (High-Electron- Mobility-Transistors). The possible origin of the mechanisms responsible for dynamic RON in these devices has been postulated. Through our new technique, the impact of high-power stress on dynamic RON has been investigated as well. The results emphasize the importance of studying dynamic RON characteristics over very short time scale when conducting reliability studies of GaN transistors. Secondly, high-voltage GaN-on-Si MIS (Metal-Insulator-Semiconductor) HEMTs designed for > 600 V switching operation have been investigated. Excessive electron trapping leading to total current collapse has been observed. We have carried out an extensive characterization of this phenomenon and we have proposed "Zener trapping" as the responsible mechanism. In this view, electron trapping takes place inside the AlGaN/GaN heterostructure through a tunneling process under high-electric-field. The understanding derived here suggests that this effect can be mitigated through attention to defect control during epitaxial growth and appropriate design of the field plate structure of the device. Our findings in this thesis provide a path to achieve high performance GaN power transistors with minimum dynamic RON effects.
by Donghyun Jin.
Ph. D.
Asgarifar, Hajarossadat. "Application of high voltage, high frequency pulsed electromagnetic field on cortical bone tissue." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53105/1/Hajarossadat_Asgarifar_Thesis.pdf.
Dimarino, Christina Marie. "Design and Validation of a High-Density 10 kV Silicon Carbide MOSFET Power Module with Reduced Electric Field Strength and Integrated Common-Mode Screen." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/86596.
Ph. D.
Electricity is the fastest-growing type of end-use energy consumption in the world, and its generation and usage trends are changing. Hence, the power electronics that control the flow and conversion of electrical energy are an important research area. Advanced power electronics with improved efficiency, power density, reliability, and functionality are critical in data center, transportation, motor drive, renewable energy, and grid applications, among others. Wide-bandgap power semiconductors are enabling power electronics to meet these growing demands, and have thus begun appearing in commercial products, such as traction and solar inverters. Looking ahead, even greater strides can be made in medium-voltage systems due to the development of silicon carbide power devices with voltage ratings exceeding 10 kV. The ability of these devices to switch higher voltages faster and with lower losses than existing semiconductor technologies will drastically reduce the size, weight, and complexity of medium-voltage systems. However, these devices also bring new challenges for designers. This dissertation will present a package for 10 kV silicon carbide power MOSFETs that addresses the enhanced electric fields, greater electromagnetic interference, worsened dynamic imbalance, and higher heat flux issues associated with the packaging of these unique devices. Specifically, due to the low and balanced parasitic inductances, the power module prototype is able to switch at record speeds of tens of nanoseconds with negligible ringing and voltage overshoot. An integrated common-mode current screen contains the current that is generated by these fast voltage transients within the power module, rather than flowing to the system ground. This screen connection simultaneously increases the partial discharge inception voltage by reducing the electric field strength at the triple point of the insulating ceramic substrate. Further, field-grading plates are used in the bus bar to reduce the electric field strength at the module terminations. The heat flux is addressed by employing direct-substrate, jet-impingement cooling. The cooler is integrated into the module housing for increased power density.
Stan, Nikola. "Complete Measurement System for Measuring High Voltage and Electrical Field Using Slab-Coupled Optical Fiber Sensors." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7053.
Johnstone, Paul Trevor. "Applications of High Voltage Power Supplies in the Purification of Water." Thesis, University of Canterbury. Electrical and Computer Engineering, 2001. http://hdl.handle.net/10092/1181.
Li, M. S. F. "Investigating the effects of applying a high voltage DC electric field in a flame using a point to plane electrode arrangement." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1433168/.
Holmgren, Jens. "Investigation of alternative current measurements in high-voltage applications." Thesis, Linköping University, Department of Science and Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8149.
ABB:s MACH2 system uses a number of currents to ignite thyristors for AC/DC-trassfformation and they are measured for control and protection. The measurement methods used today has major drawbacks. Two alternative techniques are investigated, one based on the Hall-Effect (HED) and the other based on Anisotropic Magnetoreistanse (AMR), both techniques sensing the magnetic field produced by currents in a conductor. The HED hawe low sensitivity so some kind of flux concentrators is needed. This adds volume, costs and complexity to the device. The AMR technique is much more sensitive than the HED. Unfortunately AMR are also much more sensitive for high over currents that may damage the devise, and they are not as common on te market. By testing linearity, step response and frequency dependency for some components, my conclusion is that HED components with toroidal flux concentrators utilizing magnetic feedback (Closed Loop, CL) may be used in this particular application. A drawback with CL are that they, when measuring sharp edged step signals, suffer from overshoots at the output that might activate the over current protection.
Zavattoni, Laëtitia. "Conduction phenomena through gas and insulating solids in HVDC gas insulated substations, and consequences on electric field distribution." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT063/document.
The emergence of renewable energy leads to a development of new technologies for energy distribution across long distances. The latter will be based on High Voltage Direct Current (HVDC) to avoid capacitance losses. This network is interconnected using Gas Insulated Substation (GIS), which insulation is composed of pressurized gas (SF6) and solid insulators (epoxy resin), which have to withstand HVDC. The electric field is not anymore determined by permittivity of materials, but by resistivities and charge accumulation. In the case of an insulator with an interface with gas, electrons or ions will move across electric field lines and will charge the surface of the solid insulator. The behavior of insulator's properties (gas and solid) constitutes a major challenge for the development of HVDC GIS, to understand the charge relaxation/accumulation mechanisms.In this work, the characterization of solid insulator has first been investigated, based on a low-noise current measurement method. It is thus possible to measure the leakage current through samples and onto their surface, in a pressurized gas, at high electric field and for different temperatures. Those measurements permit to evidence that both volume and surface resistivities are strongly impacted by the increase of temperature and water concentration. It has also been shown that surface resistivity has a non-linear behavior with electric field. A numerical model was developed, to simulate experimental results, showing that the surface properties of the insulator can be implemented.Furthermore, the insulating properties of the gas were also investigated through different electric field geometry (coaxial and uniform), in order to estimate the contribution of current through gas on the charge accumulated on solid insulators. It has been found that a non-negligible current passes through the gas (~pA to nA). To determine the mechanisms responsible for such currents, the latter has been characterized depending on several parameters (electrode surface roughness, material nature, electric field, temperature and relative humidity). It revealed that the variations of currents are strongly impacted by the conditioning of the device and thus by the relative humidity adsorbed on electrodes and enclosure surfaces. In presence of a dry system (dry gas and device) low current were measured (~pA), which increases with temperature. On the contrary, in case of a “wet” system (humid gas and device) the current decreases with increasing temperature. Those results combined with the influence of the electrode roughness, strongly suggest a mechanism of charge injection at the electrode surface, enhanced by water adsorption.Finally, the results obtained for both solid and gaseous insulations are used to develop a numerical model with a shape close to the industrial application, and observe the modification of electric field distribution in presence of water concentration and temperature gradient. An estimation of current flowing through the insulator and gas is thus possible in case of uniform and gradient temperature.In conclusion, this work gives the variations of both volume and surface resistivities in an epoxy resin with temperature and electric field. It also evidences the major influence of relative humidity and temperature on charge injection mechanisms which contribute to the current measured through gas. The extensive characterization performed, enables to develop a simulation which predicts the variations of electric field distribution within an HVDC GIS
Fielding, Trevor J. "An investigation of the field electron emission processes responsible for the flashover of high voltage vacuum devices." Thesis, Aston University, 1986. http://publications.aston.ac.uk/8050/.
Zabihi, Sasan. "Flexible high voltage pulsed power supply for plasma applications." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/48137/1/Sasan_Zabihi_Sheykhrajeh_Thesis.pdf.
Sarkis, Julia Ribeiro. "Extração de compostos bioativos de tortas de nozes e sementes e aplicação de tecnologias elétricas no gergelim." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/96642.
The goal of the present work was to study different technologies in the extraction of oil from sesame seed and phenolic compounds and proteins from sesame cake. This study is divided in four parts. The first part aimed to extract water-soluble compounds from different seed and nut cakes under the same conditions and compare the phenolic content and antioxidant activity of the extracts. For the first portion of the study, seed cakes of sunflower, pumpkin, flaxseed and defatted sesame, and nut cakes of almond, pecan, macadamia and hazelnut were used in the experiments. The extract from pecan nut cake presented the highest amounts of all compounds analyzed, followed by sunflower seed and hazelnut cake extracts. These samples also had the highest antioxidant activities. The following steps of the work focused on sesame only. The second part of the work aimed to optimize the extraction of total phenolics and lignans from sesame seed cake. Initially, a second-order polynomial model was set up to predict the responses in different temperatures, solid/solvent ratios and ethanol concentrations. The response variables were the concentrations of total phenolics, sesamin, sesaminol triglucoside and antioxidant activity of the extracts. Among the analyzed compounds, ST is presented in the highest quantity in sesame cake. Solid to liquid ratio and ethanol concentration where the most important factors affecting extraction, whereas temperature showed reduced influence. In the third part of this work, the aim was to evaluate alternative methodologies in the extraction of phenolics and proteins. The technologies used were pulsed electric fields (PEF) and high voltage electric discharges (HVED). These methods were used as pre-treatments, prior to diffusion. Result show that PEF and HVED were efficient and increased the extraction yield for phenolic compounds, lignans and proteins from the cake. The use of different percentages of ethanol was also significant in this stage; however, the effect of this parameter was reduced when the electrical treatments were used. In the same way, temperature also showed a smaller influence on the results when the pre-treatments were used. The observed behaviors suggest that the use of PEF and HVED increases extraction efficiency. Finally, the goal of the last part of the work was to improve oil expression from sesame seeds, using the aforementioned technologies. These experiments show a significant effect of both PEF and HVED. It was observed an increase of the amount of oil extracted with the energy input applied to the seeds. When compared both technologies, HVED showed a more expressive effect then PEF.
Serrano, Guillermo J. "High Performance Analog Circuit Design Using Floating-Gate Techniques." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19819.
Delsart, Cristele. "Champs électriques pulsés et décharges électriques de haute tension pour l’extraction et la stabilisation en oenologie." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21982/document.
The wine industry needs to find solutions in the coming years to reduce its carbon footprint by 20% and quickly propose alternatives to sulphur dioxide usage. This work on pulsed electric fields offers wine professionals an eco-innovation that could help to address these two issues. Eco-innovation is increasingly seen as the key to future competitiveness in the context of sustainable development. However, before being integrated in wine production, eco-innovation must demonstrate its performance and efficiency without compromising product quality and consumers safety so that it could be approved by government authorities (OIV, EU ...). As such, this thesis has received a joint financial support from the CIVB and the ADEME. The principle of Pulsed Electric Field (PEF) is to apply to a product; electrical pulses of a few kilovolts in a very short period time (a few microseconds) and then repeated n times. During treatment (grapes, grape must or wine) cells transmembrane potential increases till the induction of pores in the membranes. The irreversibility of the pores leads not only to the extraction of cellular components but also cell death. Thus, depending on the time of this technology application in winemaking and operating parameters, allows the extraction of sensory interests compounds such as polyphenols or the inactivation of microorganisms. PEF takes into account three important aspects to the sustainability of a technology: environment, economy and quality. This technique has a number of advantages for wine producers: clean, fast, inexpensive, efficient, industrializable and automated. Compared to other treatments such as pasteurization, sterile filtration, thermovinification, hot or cold maceration, cryoextraction or flash-release, its energy consumption is low (a few tens of kWh / tonne). PEF technology is environmentally friendly, as it requires little energy and no chemical inputs. It is fast and efficient because the processing time is only a few tens to hundreds of milliseconds. Finally, this technique is a non-thermal and therefore does not degrade the heat-sensitive molecules such as flavours. The objectives of this research work was to understand the effect of PEF on the cells, to determine the processing parameters during the extraction of compounds of interest grapes and to inactivate microorganisms in order to stop alcoholic fermentation of sweet wines and stabilize microbiologically red wines before bottling maintaining the quality of the processed product
GALLESI, FEDERICO. "Investigation, Experimental Development, and Field Application of Non-Invasive Sensors for Partial Discharge Measurement." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1082296.
Brianceau, Silène. "Vers une amélioration quantitative et qualitative de l'extraction des composés phénoliques du marc de raisin rouge à l'aide d'électrotechnologies." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2249/document.
This work aims at studying the effect of alternative technologies for the processing of winery byproducts on the improvement of extraction yields at laboratory scale. Their impacts on the biochemical quality of the extracts obtained from grape pomace were evaluated by the characterization of the extracted compounds. A comparative study on the effects of different alternative pre-treatment (pulsed electric field (PEF), high voltage electric discharges (HVED) and ultrasounds (US)) of aqueous suspensions of red grape pomace, prior to the extraction step, was realized with the specific objective of understanding the induced phenomena. The electroporation induced by PEF may allow the specific recovery of anthocyanins that are located in the upper cell layers of the hypodermis by facilitating the solvent penetration to particular skin tissues of grape. The location of targeted compounds with respect to tissue structures seems to be a key issue to optimize their extraction. As a consequence, we subsequently examined the feasibility of a PEF pre-treatment of relatively low humidity grape pomace for the enhancement of bioactive compounds extraction. We demonstrated that a relatively dry pomace (RH ≈ 55 %) can be effectively treated by PEF after optimal densification using a suitable configuration of the PEF cell. The PEF pre-treatment of a densified fermented grape pomace, at moderate electric field strengths, requires less output current and lower specific energy and is also more efficient for the selective recovery of anthocyanins than Hi-PEF pre-treatment of an aqueous suspension of grape pomace. We finally focused on the treatment of rehydrated grape pomace following the diffusion step. The enhancement of pressing of the grape pomace by ohmic heating allowed the recovery of two fractions: a solid fibrous residue partly dehydrated which could be further valorized as an agro-material or in feeding, and an extract, particularly rich in bioactive components.The technical-economic assessment shows that the successive application of electro-technologies (pre-treatment of grape pomace in dry environment by PEF followed by a pressing step assisted by ohmic heating) lead to an improvement of extraction yields of about 30 % compared to the conventional method. This mass improvement offset the increased production costs (+ 2.7 % compared to the conventional process) by reducing the total production costs of the extract (7.3 €/kg vs 9.4 €/kg for the conventional process)
Jaffré, Yoann-nicolas. "Optimisation de réacteurs à plasmas non-thermiques pour le traitement des oxydes d'azote." Thesis, Ecully, Ecole centrale de Lyon, 2010. http://www.theses.fr/2010ECDL0022/document.
Despite recent technological advances, thermal combustion in vehicles still generates a large amount of polluting gases that pure catalytic systems are unable to treat efficiently during the various phases of motor function. Nitrogen oxides are among the more problematic of the polluting gases, and a solution for their removal is critical. This work is aimed at the implementation of a solution using non-thermal plasma. The control and understanding of electrical discharges in gas enables to generate non-thermal plasmas, where only the electrons are raised to a high temperature. A non-thermal plasma treatment does not significantly heat the gas, but it still triggers important molecular changes. Under the influence of intense electric fields and depending on the initial gas composition, nitrogen oxides are either oxidized or reduced. In order to increase the gas reactivity, different geometric configurations of the reactors have been optimized and implemented. The optimization of each configuration is based on calculations of the electrostatic field, for which the amplitude of applied voltage was kept lower than 20 kV. Some of the reactors were constructed with dielectric barriers with varying arrangements, sizes, and materials. To evaluate reactor treatment efficiency of nitrogen oxides, a specialized experimental bench was constructed. Different voltage sources were tested, and the discharge was analyzed via voltage and current measurements. The experiments showed that 80 % of the nitrogen oxides in nitrogen could be reduced usinga wire-cylinder configuration with a suitable intermediate frequency AC voltage source
Mohamad, Isa Muammar Bin. "Low Noise Amplifiers using highly strained InGaAs/InAlAs/InP pHEMT for implementation in the Square Kilometre Array (SKA)." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/low-noise-amplifiers-using-highly-strained-ingaasinalasinp-phemt-for-implementation-in-the-square-kilometre-array-ska(31b6cbae-7b7e-43fe-a612-b3555dd2263d).html.
Кессаев, Александр Геннадиевич. "Водные триинги в силовых кабелях при действии сильного электрического поля и техника их обнаружения." Thesis, НТУ "ХПИ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/26761.
The thesis for a candidate degree in technical sciences, speciality 05.09.13 – Technics of Strong Electric and Magnetic Fields. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2016. The thesis is devoted to the detection technology of water treeing in medium voltage power cables of coaxial design with a water barrier under the action of strong electric fields on the basis of mathematical modeling of spherical particles of water in the crosslinked polyethylene insulation and physical modeling of the humidification process of cable samples in the laboratory. Based on the proposed mathematical model of water treeing as clusters of spherical shape in the crosslinked polyethylene insulation of the high-voltage power cable of coaxial design with axial symmetry, the region of strong electric field has been shown to be a function of size and distance between spherical inclusions. Based on the simulation results, the technics of impulse reflectometry in the time domain has been confirmed to be as one of the promising methods for diagnosing operational irregularities (ellipticity, eccentricity, water treeing) in high voltage power cables. The results of physical modeling of accelerated aging have shown the effectiveness of the high-frequency dielectric spectroscopy technics for the detection of free water in the polymer insulation of new cables and aged in a wet environment. Using the measurements technics of dielectric absorption the informative diagnostic parameters of moistened cross-linked polyethylene insulation have been shown to be absorption currents measured at 15, 30 and 60th seconds after applying the high constant test voltage, and the dynamic of change of insulation resistance depending on the applied high DC voltage.
El, Kantar Sally. "Valorisation des coproduits issus des industries d’agrumes : extraction des molécules bioactives par des technologies innovantes." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2440/document.
This work consists of the valorization of citrus by-products with innovative technologies. Citrus pressing produces millions of tons of waste per year worldwide. This waste (peels, pulps and seeds) is generally dedicated to animal feed or eliminated by composting or incineration. However its content in bioactive molecules leads to several ways of valorization. Since peels present about half of the citrus waste mass, studies have been focused on the valorization of citrus peels by the extraction of bioactive compounds. Conventional methods generally used for the extraction of bioactive compounds (solid-liquid extraction, hydrodistillation) have several disadvantages such as the use of expensive and toxic solvents, long extraction times and high energy consumption. For this reason, several innovative non-thermal technologies such as Pulsed Electric Fields (PEF), High Voltage Electrical Discharges (HVED) and Ultrasounds (US) and thermal treatments such as microwaves (MO) and infrared (IR) have been tested for the valorization of citrus by-products. Whole citrus fruits (oranges, pomelos, lemons) were PEF treated at an intensity of 3 kV/cm, then citrus juice and polyphenols were extracted by pressing. The study of the PEF-induced cell permeabilization was conducted by several methods and showed that the degree of damage varied according to the type of the treated fruit. The electroporation of the cells induced by the PEF, allowed an increase the juice yields after pressing and improved the liberation of the polyphenols from the citrus peels into the juice. This explains the possibility of obtaining a juice rich in polyphenols by treating the whole fruits with PEF before pressing. Among the solvents tested for the extraction of polyphenols from citrus peels, water is the least effective. The addition of 20% glycerol to water changed the polarity of the medium and improved the extraction of the polyphenols. The use of an enzyme mixture enhanced the release of the polyphenols related to the polysaccharides. Deep eutectic solvents have been as effective as hydroethanolic mixtures. To improve the yields and the kinetics of extractions in the different green solvents and in the enzyme mixture, citrus peels were pretreated with HVED in water. The mechanical effect of HVED, based on the fragmentation of the peels has improved the extraction of polyphenols in the various solvents. The intensification of polyphenols extraction was also conducted by IR and US. The extraction of polyphenols by IR was optimized using the surface response methodology. IR heating did not alter the extracted polyphenols which have significant antifungal and anti-mycotoxinogenic activities. The pretreatment of citrus peels with IR weakened the cell structures, increasing thus the diffusion of polyphenols during US treatment
Ng, Wing Lun. "Low-voltage high-frequency CMOS transformer-feedback voltage-controlled oscillators /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?ECED%202006%20NG.
Dale, Joel Kelly. "Electric field lines and voltage potentials associated with graphene nanoribbon." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2471.
Кєссаєв, Олександр Геннадійович. "Водяні триінги в силових кабелях при дії сильного електричного поля та техніка їх виявлення." Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/26759.
The thesis for a candidate degree in technical sciences, speciality 05.09.13 – Technics of Strong Electric and Magnetic Fields. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2016. The thesis is devoted to the detection technology of water treeing in medium voltage power cables of coaxial design with a water barrier under the action of strong electric fields on the basis of mathematical modeling of spherical particles of water in the crosslinked polyethylene insulation and physical modeling of the humidification process of cable samples in the laboratory. Based on the proposed mathematical model of water treeing as clusters of spherical shape in the crosslinked polyethylene insulation of the high-voltage power cable of coaxial design with axial symmetry, the region of strong electric field has been shown to be a function of size and distance between spherical inclusions. Based on the simulation results, the technics of impulse reflectometry in the time domain has been confirmed to be as one of the promising methods for diagnosing operational irregularities (ellipticity, eccentricity, water treeing) in high voltage power cables. The results of physical modeling of accelerated aging have shown the effectiveness of the high-frequency dielectric spectroscopy technics for the detection of free water in the polymer insulation of new cables and aged in a wet environment. Using the measurements technics of dielectric absorption the informative diagnostic parameters of moistened cross-linked polyethylene insulation have been shown to be absorption currents measured at 15, 30 and 60th seconds after applying the high constant test voltage, and the dynamic of change of insulation resistance depending on the applied high DC voltage.
Bell, Simon Colin. "High-voltage partial-core resonant transformers." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/2161.
Kopelvski, Maycon Max. "Sistema de caracterização elétrica de dispositivos emissores de campo." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-28032008-174207/.
At this work is presented the development of a field emission devices trial system to render possible to obtain the electrical characteristics of the field emission devices. Here are shown some results taken from some trials. During the development of the trial system, it was used at the programming microcontroller stage, the environment of programming supplied by the manufacturer of the microcontroller. At this development, peripheral of input and output from the microcontroller, like, keyboard reading, USART manipulation, SPI manipulation and analogic to digital converters were used. At the microcontroller were implanted routines of configuration, customing and display sweeping, besides the transmission and the receiving of instructions came from the computer. For computer, a program was elaborated dedicated for manipulation of the trials system applying the virtual instrumentation concept, storing readings of the trials as well as the visualization \"on-line\" of the course of the trial through available graphs in the program. As an important result of this work has the establishment of a system for trial of field emission devices controlled on place or remotely, system that is composed by hardware and software in which were made several trials with acquisition and data manipulation and the presentation of received information.
Naredo, V. José Luis A. "Communication frequency response of high voltage power lines." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26725.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
Buchan, John G. "Partial discharge measurements in high voltage motors." Thesis, Robert Gordon University, 1987. http://hdl.handle.net/10059/617.
Bialek, Thomas Owen. "Evaluation and modeling of high-voltage cable insulation using a high-voltage impulse." Diss., Mississippi State : Mississippi State University, 2005. http://library.msstate.edu/content/templates/?a=72.
Mugala, Gavita. "High frequency characteristics of medium voltage XLPE power cables." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-560.
Bolund, Björn. "Electric Power Generation and Storage Using a High Voltage Approach." Doctoral thesis, Uppsala University, Department of Engineering Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6833.
Production and consumption of electricity have grown enormously during the last century. No mater what the primary source of energy is, almost all generation of electricity comes from conversion of a rotational movement in a generator. The aim of this thesis is to see how high voltage technology influence production and storage of electricity. Power flow in the generators used to convert mechanical movement to electric energy is analyzed using Poynting‘s vector. The impact of new generator technology for efficient extraction of hydroelectric power is shown. Simulation of a large permanent magnet turbo generator is presented. A flywheel storage system for electric vehicles utilizing high voltage technology is also presented. In pulsed power applications, a cheap method for intermediate storage of energy during milliseconds, which enables an inductive primary storage is presented and experimentally tested.
Gonzalez-Torres, Juan Carlos. "Transient stability of high voltage AC-DC electric transmission systems." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS041.
The new policy frameworks adopted by national authorities has encouraged the large scale-integration of Renewable Energy Systems (RES) into bulk power systems. The large-scale integration of RES will have consequences on the electricity transmission system as it is conceived today, since the transmission of bulk power over long distances could lead the existing transmission systems to work close to their limits, thus decreasing their dynamic security margins. Therefore more complex transmissions systems are needed.Under this scenario, HVDC transmission systems raise as the most attractive solution for the reinforcement and improvement of existing AC networks, not only using point-to-point configurations, but also in a Multi-Terminal configuration. The introduction of HVDC transmission systems will eventually result in a hybrid high voltage AC/DC power system, which requires to be analyzed as a unique system in order to understand the interactions between the AC network and the DC grid.This thesis addresses the transient stability analysis of hybrid AC/DC electric transmission systems. More in particular, two questions sought to be investigated: What is the impact of a DC contingency on AC transient stability? How can we take advantage of the of DC transmission systems as control inputs in order to enhance AC transient stability?In the first part of this work, the mathematical models of the hybrid AC/DC grid are described as well as the necessary tools for the analysis of the system taking into account its nonlinear nature. Then, a thorough analysis of transient stability of the power system in the particular case of a DC fault and the execution of the corresponding protection strategies is done. As a complement, stability indicators and tools for sizing future MTDC grids in order to respect the constraints of existing protection strategies are proposed.The second part of the thesis addresses the control proposals for the modulation of power references of the HVDC transmission systems with the purpose of transient stability enhancement of the surrounding AC system. Firstly, we focus our study in the nonlinear control of point-to-point HVDC links in hybrid corridors. Fast power compensation, injection of damping power and injection of synchronizing power are identified as the mechanisms through which HVDC systems can improve stability margins.Finally, a control strategy for transient stability enhancement via active power injections of an MTDC grid is proposed. Using communication between the stations, the proposed decentralized control injects damping and synchronizing power between each pair of converters using only measurements at the converters level. The proposed implementation allows to fully use the available headroom of the converters by dealing with power limits in a decentralized way
Benwell, Andrew L. Kovaleski Scott D. "A high voltage piezoelectric transformer for active interrogation." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6847.
Shafran, John Sawa. "A MEMS-based, high-resolution Electric-Field meter." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33358.
Includes bibliographical references (p. 169-172).
In MEMS-based inertial sensors, such as accelerometers and gyroscopes, known electrical waveforms are applied to a modulating capacitive element to determine an unknown deflection. However, the inverse of this scheme can also be exploited - the capacitive element can be deterministically modulated to measure an electrostatic variable. This thesis presents the design, analysis, and evaluation of such a sensor -a MEMS-based, high-resolution electrostatic field-meter (ESF) - using the Analog Devices iMEMS process. High-resolution sensing is achieved by optimizing the interface electronics for low-noise operation and applying feedback techniques to enhance the range-of-motion of the MEMS capacitive structure. The entire system consists of three components: the MEMS capacitive structure and two circuit subsystems - the sense block and the drive loop. The MEMS structure acts as a transducer to generate a dynamic current that is proportional to the magnitude and polarity of the electric field incident on the sensor. The drive loop is a closed feedback loop that modulates the MEMS capacitive structure at its resonant frequency to maximize its displacement and the magnitude of the dynamic current. The sense block ultimately converts the dynamic current into a dc voltage that is proportional to the magnitude and polarity of the incident electric field. The critical, front-end component of the sense block, a transimpedance amplifier, is implemented with a low-noise operational amplifier for optimum sensing resolution.
by John Sawa Shafran.
M.Eng.
Tong, Sai-kit. "A computer-aided measurement system for monopolar high-voltage direct-current coronating lines /." [Hong Kong] : University of Hong Kong, 1986. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12321771.
Rainbird, Paul L. "Prediction of temperature rise in low voltage high current electrical switchboards." Thesis, Queensland University of Technology, 1990. https://eprints.qut.edu.au/36452/1/36452_Rainbird_1990.pdf.
Crnojacki, Zorica. "Extra high voltage transmission corridor siting : technical, public, institutional and regulatory considerations /." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-10032007-171749/.
Vazquez, Kalty. "Synthesis of Carbon Nanotubes Using High Voltage and High Frequency Induction Field." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/1031.
湯世傑 and Sai-kit Tong. "A computer-aided measurement system for monopolar high-voltage direct-current coronating lines." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B31207467.
Goss, Ben. "Degradation and life time prediction of high voltage insulation materials." Thesis, Queensland University of Technology, 2001.
Mathieson, Grant Alexander. "Interfacing solar panels with a high voltage electric vehicle battery bus." Thesis, University of Canterbury. Department of Electrical and Electronic Engineering, 1993. http://hdl.handle.net/10092/2352.