Thesis (Ph.D.) -- Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph.D.)--Victoria University (Melbourne, Vic.), 2009.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η μελέτη της συμπεριφοράς εναέριων γραμμών και υπόγειων καλωδίων μεταφοράς υψηλής τάσης έναντι κεραυνών. Για την εξυπηρέτηση του σκοπού αυτού, γίνεται προσομοίωση ενός υβριδικού δικτύου, αποτελούμενου τόσο από εναέριες γραμμές μεταφοράς όσο και από υπόγεια καλώδια, και μελέτη των μεταβατικών υπερτάσεων που εμφανίζονται σε αυτό λόγω κεραυνικών πληγμάτων σε έναν από τους αγωγούς προστασίας του τερματικού πυλώνα, όπου πραγματοποιείται η διασύνδεση εναέριας γραμμής-υπόγειου καλωδίου. Στο πρώτο κεφάλαιο παρατίθενται κάποια θεωρητικά στοιχεία σχετικά με τις ατμοσφαιρικές υπερτάσεις. Αναλύονται τα είδη των κεραυνών, οι βασικές παράμετροι και τα κύρια χαρακτηριστικά τους. Επιπλέον, περιγράφονται οι επιπτώσεις από κεραυνικά πλήγματα και ο τρόπος εύρεσης της συχνότητας με την οποία συμβαίνουν κεραυνοί ανά περιοχή. Στο δεύτερο κεφάλαιο γίνεται μία εισαγωγή στα Συστήματα Ηλεκτρικής Ενέργειας και αναπτύσσονται τα βασικά στοιχεία των εναέριων γραμμών και των υπόγειων καλωδίων μεταφοράς ηλεκτρικής ενέργειας. Επίσης, πραγματοποιείται μία σύγκριση αυτών των δύο τρόπων μεταφοράς ηλεκτρικής ενέργειας, παρουσιάζοντας τα θετικά και αρνητικά στοιχεία καθενός από αυτούς. Στο τρίτο κεφάλαιο εξετάζονται τα είδη σφαλμάτων και τα αίτια δημιουργίας αυτών στις γραμμές μεταφοράς ηλεκτρικής ενέργειας. Επιπλέον, δίνονται κάποια βασικά χαρακτηριστικά για την κυματομορφή του κεραυνικού ρεύματος. Στο τέταρτο κεφάλαιο αναλύεται η μόνωση και η προστασία τόσο των εναέριων γραμμών όσο και των υπόγειων καλωδίων έναντι κεραυνικών πληγμάτων. Εξετάζονται ακόμα οι μηχανισμοί που εγείρουν υπερτάσεις στη γραμμή μεταφοράς. Έπειτα, για τον καθορισμό της θέσης των αγωγών προστασίας της γραμμής, περιγράφονται οι μέθοδοι της μέγιστης γωνίας αλλά και η ηλεκτρογεωμετρική μέθοδος. Στο πέμπτο κεφάλαιο αναπτύσσονται τα επιμέρους στοιχεία του υπολογιστικού προγράμματος ATP-EMTP, το οποίο θα αποτελέσει το μέσο εξομοίωσης για την παρούσα εργασία. Αναφέρονται τα σημεία υπεροχής και η καταλληλότητά του για τέτοιου είδους αναλύσεις και παρουσιάζονται τα επιμέρους υποπρογράμματα από τα οποία αποτελείται. Ιδιαίτερη έμφαση δίνεται στο ATPDraw, το οποίο είναι το κύριο όργανο της εξομοίωσης. Στο έκτο κεφάλαιο περιγράφεται αναλυτικά το υβριδικό δίκτυο μεταφοράς υψηλής τάσης που χρησιμοποιείται στην εξομοίωση και αναλύονται τα στοιχεία που το αποτελούν, δηλαδή οι εναέριες γραμμές και τα υπόγεια καλώδια. Επιπλέον, παρουσιάζονται τα αποτελέσματα των εξομοιώσεων και οι γραφικές παραστάσεις των υπερτάσεων στα διάφορα σημεία του κυκλώματος, εξαιτίας κεραυνικών πληγμάτων, των οποίων το εύρος αυξάνει σε κάθε εξομοίωση. Στη συνέχεια ελέγχεται η επικινδυνότητα των υπερτάσεων που εγείρονται για τα διάφορα μεγέθη κεραυνικού ρεύματος και εάν ο εξοπλισμός σε διαφορετικά σημεία του δικτύου αντέχει τις υπερτάσεις αυτές ή καταστρέφεται. Από τα αποτελέσματα προκύπτει ότι επικίνδυνες υπερτάσεις παρατηρούνται σε τμήματα της εναέριας γραμμής μεταφοράς πλησίον του σημείου κεραυνικού πλήγματος. Αντίθετα, το υπόγειο τμήμα του δικτύου αποδεικνύεται πιο ανθεκτικό, καθώς δεν εγείρονται επικίνδυνες υπερτάσεις ακόμα και για πολύ υψηλό κεραυνικό ρεύμα. / The purpose of this diploma thesis is the study of the behavior of overhead transmission lines and underground transmission cables against lightning. In favor of this purpose, a simulation of a hybrid transmission network takes place, which is composed of both overhead lines and underground cables, in order to examine transient overvoltages. These overvoltages are raised due to a lightning that strikes the shield wire of the terminal tower, where the interconnection of overhead line to underground cable takes place. Chapter one presents the basic theory concerning atmospheric discharges. It describes the different types of lightning strikes, their parameters and basic characteristics. Furthermore, it analyzes the consequences of lightning and how to find the frequency that a lightning takes place in an area. At the second chapter there is an introduction in the systems of electric energy and a presentation of the basic characteristics of overhead lines and underground cables. In addition, there is a comparison between those two means of electricity transmission. Chapter three examines the types of errors and the causes of them at the electricity transmission lines. Moreover, it gives the basic parameters of the lightning current waveform. Chapter four analyzes the insulation and protection of both overhead lines and underground cables against lightning. It also examines the mechanisms that raise overvoltages at the transmission lines. Afterwards, there are described two methods on how to define the place of shield wires at a transmission line. Chapter five describes the ATP-EMTP simulation program, which is a specific software to simulate power systems. Its superiority for research like the present one is high lined and special emphasis is given to ATPDraw which is the main tool for the simulation. At chapter six there is a detailed analysis of the hybrid network used in this simulation and of its basic components, which are the overhead lines and the underground cables. Furthermore, there is a presentation of the results of the simulation and the graphs of the overvoltages at different spots of the network, due to lightning strikes. Afterwards, there is an evaluation of the risk of overvoltages that are raised for different lightning current sizes and if the equipment at different spots of the network sustains these overvoltages or it is destroyed. From the results, it is concluded that dangerous overvoltages are raised at sections of the overhead line near the lightning strike. On the contrary, the underground section of the network appears to be more resistant, as there are not raised dangerous overvoltages, even when the lightning current was too high.

Kraven på ett driftsäkert elnät ökar hela tiden i takt med att elanvändning blir allt viktigare i dagens samhälle. Luftledningar byts ut med markkabel och möjlighet till reservmatningar samt bra elkvalitet är av hög prioritering. Skicket på elnätets utrustning försämras med åren och kommer med tiden behöva bytas ut. Med uppdrag från Uddevalla Energi AB har siffror tagits fram berörande spänningsfall, kapacitiv jordfelsström och belastningar vid normaldrift och reservmatning, samt ålder och typ på kablar i Uddevalla citys mellanspänningsnät. Den här rapporten presenterar dessa resultat och ger några förslag på ändringar om så krävs. Även en del om planerade framtida utbyggnationer tas upp och hur dessa påverkar nätet. För att få fram resultaten används Uddevalla Energis program för nätberäkning, "DpPower". Beräkningarna visade att vid normaldrift var alla värden godkända enligt tumregler som Uddevalla Energi följer. Vid reservmatning däremot var vissa linjer överbelastade, analysen visar dock tillgängliga lösningar. Ålder och status på kablar i nätet varierar stort vilket gör det svårt att specificera hur ombyggnationer ska ske. Hänsyn bör istället tas till överbelastningar. / The demand of reliable power distribution is increasing as the usage of power is increasing in the society of today. Overhead lines are replaced by underground cables, availability to reserve power supply and power quality is of high priority. The condition of the equipment deteriorates over the years and will eventually have to be replaced. By request from Uddevalla Energi, values have been provided concerning voltage drop, capacitive ground fault current and loads during normal operation and standby power supply. The types and ages of cables in Uddevalla City’s high-voltage network has also been looked at. This report presents these results and gives some suggestions for modifications if required. Planned future deployments are looked over and how these may affect the network. To obtain these results the network calculating program "DpPower" was used. The calculations presented shows that in normal operation all values are approved within the company standards that Uddevalla Energi follows. For the reserve supply however, some lines are overloaded. The analysis shows possible solutions for these issues. Age and status of cables in the network varies widely, making it difficult to specify how redevelopments should take place. Instead the overloads should be given more consideration.

Thesis (MScEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: This thesis describes the development of a GPS Based Time Stamping and Scheduling System for power system applications. These applications include Wide Area Measurements (WAMs) of electrical power system quantities and high-voltage transmission line fault location. The developed system employs a microcontrolIer and a GPS receiver to synchronise an onboard microsecond-accurate clock to a global time standard. The system is therefore able to provide an accurate GPS-synchronised time stamp of a received trigger signal for use in highvoltage transmission line fault location. The system is also able to generate a trigger signal at a pre-programmed time for initiation of data acquisition runs on electrical power systems. The system was constructed and tested in a laboratory environment. Although the system is designed to operate in stand-alone mode, a host computer software program was also developed for system control and data downloading. The software program was used to time stamp a number of trigger signals and data was downloaded to a host computer. Trigger signals were also generated at predefined times. The acquired data was validated and presented. In conclusion, the low system cost, relative to existing commercial systems, accuracy and programmability of the developed system makes it suitable for a wide variety of time-critical data acquisition applications. / AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die ontwikkeling van 'n GPS gebaseerde tyd stempel en skedulerings sisteem met die oog op kragstelsel toepassings. Ingesluit by hierdie toepassings is wye area metings op elektriese kragstelsels, asook foutopsporing op hoogspanning transmissielyne. Die ontwikkelde sisteem gebruik 'n mikrobeheerder en 'n GPS ontvanger om 'n aanboord mikrosekonde-akkurate horlosie te sinkroniseer met 'n internasionale tyd standaard. Dus kan die ontwikkelde sisteem 'n akkurate GPS gesinkroniseerde tyd stempel aan 'n snellersein heg. Hierdie tyd stempel kan gebruik word in hoogspanning transmissielyn foutopsporing. Die sisteem kan ook 'n snellersein genereer op 'n vooraf geprogrammeerde tyd. Hierdie snellersein kan gebruik word om belangrike data van elektriese kragstelsels te versamel, deur gebruik te maak van bestaande dataversamelingstelsels. Die sisteem was ontwerp en getoets in laboratorium toestande. Alhoewel die stelselontwerp is om alleenstaande te funksioneer, is 'n beheer rekenaar gebruik om, met die hulp van ontwikkelde sagteware, die sisteem te beheer en data af te laai. 'n Tyd stempel is aan 'n aantal snellerseine geheg en hierdie data is afgelaai na 'n beheer rekenaar. Die sisteem is ook geprogrammeer om 'n aantal snellerseine te genereer op vooraf gedefinieerde tye. Die data wat uit hierdie toetse versamel is, is bespreek. In vergelyking met bestaande kommersiële stelsels is die ontwikkelde stelsel se lae koste, akkuraatheid en programmeerbaarheid eienskappe wat die stelsel geskik maak vir 'n wye verskeidenheid van tyd-kritieke dataversameling toepassings.

This study investigates the static behavior and dynamic behavior of the Stonecutters Cable-Stayed Bridge, which is the third longest cable-stayed bridge in the world, when a group of 8 cables is damaged by corrosion. In this thesis, the reduction in cable cross-section area is used to simulate the corrosion level. The corroded cables are divided into 2 groups of 4 cables, arranged in symmetric and asymmetric distributions on both decks. A finite element bridge model was employed to perform the analysis. The validation of the model was established by comparing numerical results to the published results of the bridge. The model was then subjected to gravity load only to check the effects of corrosion level, the distance of the corroded cables and the distribution of the damaged cables on the decks’ deflection and cable stresses change. In the dynamic analysis, the natural frequencies and mode shapes were compared with a reference case with no corrosion-damaged cables. A recorded wind load was applied on the deck to investigate the time-history response of the mid-span in the horizontal, vertical and torsional directions, and of the tower top in the horizontal direction. Moreover, frequency analysis was performed on the time-history response, and coupled motions at certain frequencies were observed. Numerical results as the ones presented in this thesis can complement information gathered from non-destructive testing technology in detecting corrosion-damaged stay-cables in cable-stayed bridges.

This thesis provides analytical and forensic tools for data cabling, with particular focus on Ethernet cabling to assist designers and those involved in deployments in analyzing cable performance and the reasons behind the actual performance obtained. The need for higher bandwidth to accommodate increasing demand for multimedia services and data centers network infrastructure led to the formation of IEEE P802.3bq to create standards for 40GBASE-T over twisted pair cables. The 40GBASE-T is expected to offer bandwidth of up to 2000MHz over a maximum channel length of 30m. The research investigated means of predicting key performance parameters in Ethernet cabling standardization using the 40GBASE-T as an example. The performance parameters prediction method provided is equally applicable to ongoing and future high data rate Ethernet cabling standardization such as the 2.5/5GBASE-T and 50/100GBASE-T. Another problem in the Ethernet networking world is the availability of counterfeit and non-standards compliant twisted pair cables in the market. The significant amount of communications cables in the market containing copper clad aluminum cable or other non-standards compliant conductors disguised as Category 6 cables can pose serious problems to companies’ networks, the contractors or the installers. This is in view of the growing demand for internet of things (IOT) services that makes it imperative to have a reliable Ethernet driven communication network to support the required infrastructure. This thesis therefore, provides techniques that can be used to evaluate cables key performance parameters using the Feature Selective Validation method and the Kolmogorov-Smirnov (KS) test. The technique can help engineers avoid subjective judgement and make objective decisions in the selection of cables. The research provided a technique that can be used to reverse engineer impedance profile from the return loss measurement of Ethernet cables using genetic algorithms. The method can be applied in situations where time domain tests are inaccessible or only simple (magnitude) tests in the frequency domain are available and there is the need for impedance profiles of cables to evaluate their performance or physical integrity before or after installation. The method can also be useful where only simple (magnitude) tests are the only historical data available for the cables and facilities for time domain reflectometry measurements are inaccessible. This research also presented a method of evaluating and predicting NEXT in unshielded twisted pair (UTP) using Category 6 cables as an example. The results obtained from the evaluation were used to provide crosstalk parameters for fast NEXT prediction in Category 6 (UTP) cables. The research used the measured NEXT of three Category 6 (UTP) cables from different manufacturers for evaluation and validation. The evaluation and modeling method can thus be useful to engineers investigating NEXT in the design of data communication systems.

La seconde génération de rubans supraconducteurs utilisant une couche déposée et épitaxiée de supraconducteur YBa2Cu3O7-x (YBCO) est étudiée de façon intense (coated conductors). Une architecture simple à bas coût a été choisie, avec une seule couche tampon de La2Zr2O7 (LZO), épitaxiée sur un ruban de Ni95W5 texturé bi-axialement. L’objectif de cette thèse était d’identifier les paramètres pertinents du processus de texturation sur des rubans d’alliage Ni95W5 laminés par APERAM à partir d’une coulée industrielle et ceux contrôlant l’épitaxie de la couche tampon de (LZO). Le rôle de la fonctionnalisation du substrat pour l’épitaxie de cet oxyde sur la surface du métal a été en particulier étudié. Parallèlement, la faisabilité d’un procédé de recuit de texturation et de fonctionnalisation du substrat métallique au défilé, en vue d’un traitement continu pour un développement industriel, a été étudiée. / The second generation of superconducting tapes using a deposited layer and epitaxialsuperconductor YBa2Cu3O7-x (YBCO) is studied intensively (coated conductors). A simple lowcostarchitecture was chosen, with one buffer layer La2Zr2O7 (LZO), epitaxially grown on aribbon of biaxially textured Ni95W5. The aim of this thesis was to identify the relevant processparameters texturing ribbons Ni95W5 alloy rolled by APERAM from an industrial casting, andthose controlling the epitaxial buffer layer (LZO). The role of the functionalization of thesubstrate for epitaxy of the oxide on the metal surface has been particularly studied. Meanwhile,the feasibility of an annealing process and functionalization texturing of the metal substrate rollto roll, in view of a continuous treatment for an industrial development, was studied.

Made available in DSpace on 2014-06-11T19:22:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-27Bitstream added on 2014-06-13T20:49:15Z : No. of bitstreams: 1 sartin_acp_me_bauru.pdf: 2377399 bytes, checksum: d4b29001d0dcb0173350d8175fba63b3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho possui como foco principal a apresentação de proposições técnicas para a avaliação da suscetibilidade eletromagnética de cabos metálicos isolados, blindados ou não, para atender aos sistemas de supervisão, proteção, comunicação e controle de subestações de alta tensão frente às interferências eletromagnéticas provocadas pelas descargas atmosféricas, manobras de chaveamento, campo magnético na frequência de 60Hz e do efeito corona. Para a realização destas proposições foram analisados e estudados diversos cabos usados em uma subestação de 440kV. A diretriz metodológica adotada nesta pesquisa incorporou simulações de modelo computacional, ensaios laboratoriais recomendados pelas normas e publicações técnicas correlatas com a finalidade de identificar os efeitos provocados pelas interferências eletromagnéticas nesses cabos. Os resultados obtidos conduziram a uma análise da interferência eletromagnética nos diversos cabos avaliados fornecendo, assim, um valor de imunidade de cada cabo estudado. Constatou-se que os cabos sem blindagem devem ser usados com reservas e podem ser instalados em sistemas poucos sujeitos a interferências eletromagnéticas ou promover uma blindagem adicional. Os cabos blindados, menos suscetível a interferências eletromagnéticas, podem ser instalados em pátios de subestações, entretanto devem-se tomar os devidos cuidados com o aterramento da blindagem. Desta forma, a pesquisa realizada contribuiu para o desenvolvimento de um procedimento técnico para o uso adequado de cabos em questão visando minimizar os efeitos provocados pelas interferências eletromagnéticas nos sistemas de supervisão, proteção, comunicação e controle presentes em subestações de alta tensão. / The main focus of this work is the presentation of technical propositions to assessing the electromagnetic susceptibility of isolated metallic cable, shielded or not, in order to comply with the supervision, protection, communication and control systems of high voltage substations in the presence of electromagnetic interferences caused by lightning discharge, switching maneuver, electromagnetic field at 60Hz and corona effect. Several cables used in 440 kV substation were analyzed and studied for accomplishing these propositions. The methodological guideline adopted in this research has included simulations of computational models, laboratorial tests recommended by standards and technical publications correlated in order to identifying the effects provoked by electromagnetic interferences to these cables. The obtained results led to an analysis of the electromagnetic interference in the several cables assessed, thus providing a value of immunity for each cable studied. It was verified that cable without shielding must be employed with restrictions and can be installed in systems which are little subject to electromagnetic interference or to promote an additional shielding. The shielding cables less susceptible to the electromagnetic interference can be installed in substation courtyard; however, it is important to pay special attention to the grounding of the shielding. Thus, this research contributed to the development of a technical proceeding for employing the mentioned cables suitably, aiming at minimizing the effects provoked by the electromagnetic interferences in the supervision, protection, communication and control systems which are present at the high voltage substations.

Made available in DSpace on 2014-10-09T12:32:36Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:06Z (GMT). No. of bitstreams: 1 03267.pdf: 2564353 bytes, checksum: 17a5e3fd6d69d57ed9339da8c448cbba (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP