Letteratura scientifica selezionata sul tema "Wire transmission lines"

Overhead transmission line icing is one of the main factors affecting safety and reliability of power grid. This paper proposed an excitation deicing method of iced wire and theoretically revealed the ice removal mechanism under displacement excitation conditions, by taking the LGJ-70/10 glaze icing wire as the 3D model and analyzing and studying its dynamic response under the effect of displacement excitation. The simulation results show that the stress of wire icing area is enlarged with the increase of excitation displacement and frequency. Through the comparison of the compression strength experimental results on a series of different iced wires in low temperature environment, the authors found out that the stress generated from the wire icing area is greater than the crushing strength of the ice within the scope of the calculation parameters, which proved the validity and the feasibility of the method, and finally the suitable excitation displacement is determined. Following studies show that, as far as possible, it is necessary to reduce the incentive displacement and also to select the appropriate constraint length in order to avoid the line jumping that may be caused by large span ice shedding.

The use of new generation wires in the design of wide spans of overhead power lines over water barriers and large gorges can increase their transmission capacity and increase reliability. However, when large currents flow, load losses in line also increase. Thus, it is necessary to obtain a methodology for technical and economic comparison of design options for overhead power lines over large crossings, which enables to determine the most cost-effective version of the project with high mechanical reliability. For comparative analysis, five options for wide spans of overhead power lines over the river with new-generation wires of Russian production were compiled: Aluminium Alloy Conductor Steel Reinforced, Z-type (high conductivity), Thermal-Resistant Conductor, Aluminium Compozite Core Conductor, ASk2y. Option with Aluminium Conductor Steel Reinforced wire was taken as the source. For the first option, the crossing scheme E-A-A-E was selected, for the remaining options E-I-I-E scheme was considered. For the modes of maximum loads, minimum temperature and average annual conditions, the mechanical calculation of wires was carried out using the method of permissible stresses. The wire bending deflections were determined in accordance with the theory of the catenary curve. The method of integrated indicators was used to perform a technical and economic comparison of these options. The calculation results showed that among the proposed options, the most optimal is a crossing with the ACCC wire having minimum relative investment per 1 MW of transmitted electricity and minimal power loss. The transmission capacity of the line with this wire is increased by 1.8 times, and the cost of crossing is reduced by 16%. Due to the compact design of wire, the probability of ice formation on wire is reduced, and the reduced bending deflection reduces the probability of wire break due to natural environmental influences.

Overhead ground wires have been proved to be effective to protect conductors from direct lightning strikes, but breakouts of ground wires have been frequently reported. In order to prevent ground wire breakout incidents to happen, unshielded 220kV lines equipped with metal oxide arresters (MOAs) whole line have been proposed in this paper. After cancelling ground wire, lightning strike risk of transmission lines becomes much higher. In order to improve the anti-lightning abilities of unshielded transmission lines, it is necessary to obtain the lightning energy absorption ability of these MOAs. In this paper, simulation model of MOA equipped unshielded 220kV transmission line was built, the influences of lightning parameters, striking occurrence point and grounding resistance of transmission tower on the absorbed energy of MOAs were calculated, and the suggested energy absorption ability of MOA was given, which can give references for the improvement of power supply reliability of transmission lines.

In this thesis we present new approaches in the domains of soft fault detection and location in complex wire networks, based on the properties of time reversal. When addressing the detection of soft faults, the idea is to adapt the testing signal to the network under test, instead of being predefined for all the tested networks, as opposed to standard reflectometry techniques. We prove that this approach, which we name the Matched Pulse approach (MP), is beneficial whenever the system is more complex, i.e., its response is richer in echoes, which is opposed to common understanding. The MP analysis is conducted via a formal mathematical analysis, followed by simulation and experimental results validating the proposed approach. In the domain of soft fault location, and based on the DORT (Décomposition de l'Opérateur de Retournement Temporel) properties, we derive a distributive non-iterative method able to synthesize signals that focus on the fault position. Through a statistical study we analyze some of the influencing parameters on the performance of the method, and then simulation and experimental results show that the method is able to synthesize signals directly focalizing on the soft fault position, without the need for iterations.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Магістерська дисертація складається з пояснювальної записки на 106 сторінках та графічної частини на 8 листах. В роботі наведено 46 рисунків та 13 таблиць. Робота містить такі розділи: 1. Загальні відомості щодо ожеледно-вітрових навантажень та коливань проводів ПЛ. 2. Моделювання коливань проводів ПЛ з урахуванням ожеледно-вітрових навантажень. 3. Методи та засоби захисту ПЛ від вібрації та галопування. 4. Методи та засоби захисту ПЛ від ожеледно-вітрових навантажень. Актуальність роботи: Одним з найголовніших принципів сучасної енергетики є забезпечення надійної та безперебійної роботи обладнання електроенергетичних систем і електричних мереж. Для повітряних ліній електропередавання одним з актуальних є питання їх захисту від зовнішніх впливів природного походження, таких як вітрові та ожеледно-вітрові навантаження. У зарубіжних країнах немає єдиної методики нормування розрахункових кліматичних умов для проведення їх районування за інтенсивністю ожеледоутворення, тому питання організації боротьби з різними видами відкладень на проводах ліній електропередавання на сьогоднішній день поставлене першочергово і є дуже актуальним. Для швидкого та точного вирішення цього питання необхідним є уточнення всіх існуючих знань та матеріалів щодо вітрових та ожел едно-вітрових навантажень, створення комп'ютерних моделей аналізу та прогнозування даних відкладень на проводах ліній електропередавання і створення нових методів та типів захисту ліній електропередавання від впливів природного походження Мета дисертаційної роботи: Аналіз і вивчення повного циклу виникнення ожеледних відкладень на лініях електропередавання з врахуванням впливу дії вітру, аналіз впливу та створення комп'ютерної моделі ожеледно-вітрових навантажень на проводи ліній електропередавання, запропонування методик та типів захисту ліній електропередавання від ожеледно-вітрових навантажень. Об’єкт дослідження: проводи повітряних ліній електропередавання усіх класів номінальних напруг. Предмет дослідження: процес виникнення ожеледних відкладень під дією вітру та їх вплив на проводи ліній електропередавання усіх класів номінальних напруг. Ключові слова: проводи ліній електропередавання, ожеледні відкладення, ожеледоутворення, ожеледно-вітрові навантаження, захист від ожеледно-вітрових навантажень.
The master's dissertation consists of an explanatory note on 106 pages and graphic part on 8 paper. There are 46 pictures and 13 tables. The work contains the following sections: 1. General information on ice-wind loads and fluctuations of wires. 2. Modeling of fluctuations of wires of the power lines, taking into account the ice-wind loads. 3. Methods and means of protection of the submarine from vibration and galloping. 4. Methods and means of protection of submarines from ice-wind loads. Actuality of work: One of the most important principles of modern energy is to ensure reliable and uninterrupted operation of equipment of electric power systems and electric networks. One of the most urgent issues is to protect them from external influences of natural origin, such as wind and ice-wind loads. In foreign countries there is no uniform method of normalization of the calculated climatic conditions for their zoning based on the intensity of ice-forming, so the issue of organizing the fight against various types of deposits on the lines of transmission lines has been put to the fore today and is very topical. In order to quickly and accurately resolve this issue, it is necessary to clarify all existing knowledge and materials concerning wind and ice-wind loads, to create computer models of analysis and forecasting of these deposits on wires of power transmission lines and to create new methods and types of protection of transmission lines from natural influences. The purpose of the dissertation work: Analysis and study of the full cycle of occurrence of iced deposits on transmission lines, taking into account the influence of the wind, impact analysis and the creation of a computer model of ice-wind loads on the transmission lines, offering methods and types of protection of transmission lines from ice-wind loads. Object of research: conducting of overhead transmission lines of all classes of nominal voltages. Subject of research: the process of occurrence of iced ice deposits under the influence of wind and their influence on conduction lines of electric power transmission of all classes of nominal voltages.

Le vieillissement des lignes de transport d’énergie électrique est une problématique majeure des réseaux. D’ailleurs, des problèmes se posent au plan de l’évaluation de l’état des conducteurs qui, soumis aux vibrations éoliennes, sont vulnérables à l’endommagement en fatigue. Surtout présent aux pinces de suspension, ce phénomène est encore difficile à quantifier, notamment quant à la prédiction de la durée de vie résiduelle des conducteurs. D’autre part, avec le besoin croissant d’optimiser l’exploitation du réseau tout en maintenant sa fiabilité, une estimation précise de l’état d’endommagement des conducteurs est primordiale. Pour cela, une caractérisation des sollicitations à l’échelle des brins est d’abord requise. L’objectif principal de cette thèse vise donc le développement d’une stratégie de modélisation et d’analyse des conducteurs sollicités en vibrations éoliennes permettant une évaluation précise des conditions de chargement locales à l’échelle des brins, tout en tenant compte de l’effet de la géométrie des pinces de suspension. Une stratégie de modélisation 3D des solides toronnés est d’abord développée avec la méthode des éléments finis selon une discrétisation individuelle des brins par éléments poutres, capable de traiter toutes les interactions inter-filaires en frottement. Cette modélisation traduit efficacement la cinématique des torons tout en donnant accès aux charges locales. Son caractère général lui permet aussi d’être appliquée à tout problème impliquant des torons. Appliquée à l’étude des conducteurs sous l’effet des vibrations éoliennes, la stratégie conduit à une description précise de leur comportement tant au plan global en flexion que de la description des contraintes aux brins. Des estimations réalistes de durées de vie en fatigue des conducteurs sont même possibles par l’application de critères d’endommagement aux contraintes. Ensuite, les pinces de suspension sont intégrées à la stratégie de modélisation selon une représentation surfacique traitant le contact pince/conducteur. Une comparaison à des mesures expérimentales met en relief la précision de l’approche. L’analyse de la solution numérique permet l’identification des zones critiques d’endommagement en contact à chacune des couches du conducteur et révèle des informations nouvelles quant à la nature de la sollicitation des brins à la pince de suspension. Finalement, des travaux exploratoires proposent un nouveau concept d’analyse multi-échelles en combinant la modélisation numérique d’un système pince/conducteur à des essais de fatigue sur brins individuels. Une mise en œuvre préliminaire de l’approche permet de valider le concept et en jette les bases en vue de son application future. En somme, la stratégie de modélisation développée dans cette thèse constitue un puissant outil d’analyse qui ouvre maintenant la voie à une caractérisation appropriée de la fatigue des conducteurs en vue ultimement de prédire leur durée et vie résiduelle.
Abstract : The aging of overhead transmission lines is a major concern for utilities. In particular, problems arise in assessing the integrity of conductors whose exposure to Aeolian vibrations renders them vulnerable to fatigue damage. Occurring mainly at the suspension clamps, conductor fatigue is still difficult to quantify, especially regarding the prediction of their residual life. With the increasing need to optimize the power grid while maintaining its reliability, accurate evaluations of the conductor damage state become crucial. To this matter, a characterization of the stress levels at the wire scale is first required. The main objective of this thesis is therefore to develop a strategy for the modeling and analysis of conductors subjected to wind induced vibrations, allowing an accurate description of the local load conditions, while accounting for the effects of the suspension clamps. A finite element wire strand modeling strategy is first developed based on a 3D beam element discretization, considering all frictional wire interactions. The modeling approach efficiently reproduces the wire strand kinematics while giving access to the local loads. Its general formulation also allows it to be applied to any problem involving strands. Applied to the study of conductors subjected to Aeolian vibrations, the strategy leads to an accurate description of their behavior at both the global strand deformations and the wire stress description. Realistic conductor residual life estimates are even possible with the use of common damage criteria. The suspension clamps are then incorporated into the modeling strategy using a surface representation of the conductor/clamp contact. Comparisons with experimental measurements highlight the precision of the approach. The model response analysis allows now the identification of the critical damage zones within each conductor layers and reveals new information about the nature of the wire stresses at the suspension clamp. Finally, exploratory works propose a new concept of multi-scale analysis combining the numerical conductor/clamp modeling strategy to experimental fatigue tests on individual wires. A preliminary implementation of the approach validates the concept and lays the foundations for its future application. In summary, the modeling strategy developed in this thesis constitutes a powerful analytical tool which now opens the way to an appropriate characterization of conductor fatigue with the ultimate objective to eventually predict their residual life.

This thesis tackles issues of particular interest regarding analysis and design of passive components at the mm-wave and Terahertz (THz) bands. Innovative analysis techniques and modeling of complex structures, design procedures, and practical implementation of advanced passive devices are presented. The first part of the thesis is dedicated to THz passive components. These days, THz technology suffers from the lack of suitable waveguiding structures since both, metals and dielectric, are lossy at THz frequencies. This implies that neither conventional closed metallic structures used at microwave frequencies, nor dielectric waveguides used in the optical regime, are adequate solutions. Among a variety of new proposals, the Single Wire Waveguide (SWW) stands out due to its low attenuation and dispersion. However, this surface waveguide presents difficult excitation and strong radiation on bends. A Dielectric-Coated Single Wire Waveguide (DCSWW) can be used to alleviate these problems, but advantages of the SWW are lost and new problems arise. Until now, literature has not given proper solution to radiation on bends and, on the other hand, rigorous characterization of these waveguides lacks these days. This thesis provides, for the first time, a complete modal analysis of both waveguides, appropriated for THz frequencies. This analysis is later applied to solve the problem of radiation on bends. Several structures and design procedures to alleviate radiation losses are presented and experimentally validated. The second part of the thesis is dedicated to mm-wave passive components. These days, when implementing passive components to operate at such small, millimetric wavelengths, to ensure proper metallic contact and alignment between parts results challenging. In addition, dielectric absorption becomes significant at mm-wave frequencies. Consequently, conventional hollow metallic waveguides and planar transmission lines present high attenuation so that new topologies are being considered. Gap Waveguides (GWs), based on a periodic structure introducing an Electromagnetic Bandgap effect, result very suitable since they do not require metallic contacts and avoid dielectric losses. However, although GWs have great potential, several issues prevent GW technology from becoming consolidated and universally used. On the one hand, the topological complexity of GWs difficulties the design process since full-wave simulations are time-costly and there is a lack of appropriate analysis methods and suitable synthesis procedures. On the other hand, benefits of using GWs instead of conventional structures are required to be more clearly evidenced with high-performance GW components and proper comparatives with conventional structures. This thesis introduces several efficient analysis methods, models, and synthesis techniques that will allow engineers without significant background in GWs to straightforwardly implement GW devices. In addition, several high-performance narrow-band filters operating at Ka-band and V-band, as well as a rigorous comparative with rectangular waveguide topology, are presented.
Esta tesis aborda problemas actuales en el análisis y diseño de componentes pasivos en las bandas de onda milimétrica y Terahercios (THz). Se presentan nuevas técnicas de análisis y modelado de estructuras complejas, procedimientos de diseño, e implementación práctica de dispositivos pasivos avanzados. La primera parte de la tesis se dedica a componentes pasivos de THz. Actualmente no se disponen de guías de onda adecuadas a THz debido a que ambos, metales y dieléctricos, introducen grandes pérdidas. En consecuencia, no es adecuado escalar las estructuras metálicas cerradas usadas en microondas, ni las guías dieléctricas usadas a frecuencias ópticas. Entre un gran número de recientes propuestas, la Single Wire Waveguide (SWW) destaca por su baja atenuación y casi nula dispersión. No obstante, como guía superficial, la SWW presenta difícil excitación y radiación en curvas. El uso de un recubrimiento dieléctrico, creando la Dielecric-Coated Single Wire Waveguide (DCSWW), alivia estos inconvenientes, pero las ventajas anteriores se pierden y nuevos problemas aparecen. Hasta la fecha, no se han encontrado soluciones adecuadas para la radiación en curvas de la SWW. Además, se echa en falta una caracterización rigurosa de ambas guías. Esta tesis presenta, por primera vez, un análisis modal completo de SWW y DCSWW, adecuado a la banda de THz. Este análisis es aplicado posteriormente para evitar el problema de la radiación en curvas. Se presentan y validan experimentalmente diversas estructuras y procedimientos de diseño. La segunda parte de la tesis abarca componentes pasivos de ondas milimétricas. Actualmente, estos componentes sufren una importante degradación de su respuesta debido a que resulta difícil asegurar contacto metálico y alineamiento adecuados para la operación a longitudes de onda tan pequeñas. Además, la absorción dieléctrica incrementa notablemente a estas frecuencias. En consecuencia, tanto guías metálicas huecas como líneas de transmisión planares convencionales presentan gran atenuación, siendo necesario considerar topologías alternativas. Las Gap Waveguides (GWs), basadas en una estructura periódica que introduce un efecto de Electromagnetic Bandgap, resultan muy adecuadas puesto que no requieren contacto entre partes metálicas y evitan las pérdidas en dieléctricos. No obstante, a pesar del potencial de las GWs, varias barreras impiden la consolidación y uso universal de esta tecnología. Por una parte, la compleja topología de las GWs dificulta el proceso de diseño dado que las simulaciones de onda completa consumen mucho tiempo y no existen actualmente métodos de análisis y diseño apropiados. Por otra parte, es necesario evidenciar el beneficio de usar GWs mediante dispositivos GW de altas prestaciones y comparativas adecuadas con estructuras convencionales. Esta tesis presenta diversos métodos de análisis eficientes, modelos, y técnicas de diseño que permitirán la síntesis de dispositivos GW sin necesidad de un conocimiento profundo de esta tecnología. Asimismo, se presentan varios filtros de banda estrecha operando en las bandas Ka y V con altas prestaciones, así como una comparativa rigurosa con la guía rectangular.
Aquesta tesi aborda problemes actuals en relació a l'anàlisi i disseny de components passius en les bandes d'ona mil·limètrica i Terahercis. Es presenten noves tècniques d'anàlisi i modelatge d'estructures complexes, procediments de disseny, i implementació pràctica de dispositius passius avançats. La primera part de la tesi es focalitza en components passius de THz. Actualment no es disposen de guies d'ona adequades a THz causa que tots dos, metalls i dielèctrics, introdueixen grans pèrdues. En conseqüència, no és adequat escalar les estructures metál·liques tancades usades en microones, ni les guies dielèctriques usades a freqüències òptiques. Entre un gran nombre de propostes recents, la Single Wire Waveguide (SWW) destaca per la seua baixa atenuació i quasi nul·la dispersió. No obstant això, com a guia superficial, la SWW presenta difícil excitació i radiació en corbes. L'ús d'un recobriment dielèctric, creant la Dielecric-Coated Single Wire Waveguide (DCSWW), alleuja aquests inconvenients, però els avantatges anteriors es perden i nous problemes apareixen. Fins a la data, no s'han trobat solucions adequades per a la radiació en corbes de la SWW. A més, es troba a faltar una caracterització rigorosa d'ambdues guies. Aquesta tesi presenta, per primera vegada, un anàlisi modal complet de SWW i DCSWW, adequat a la banda de THz. Aquest anàlisi és aplicat posteriorment per evitar el problema de la radiació en corbes. Es presenten i validen experimentalment diverses estructures i procediments de disseny. La segona part de la tesi es centra en components passius d'ones mil·limètriques. Actualment, aquests components pateixen una important degradació de la seua resposta a causa de que resulta difícil assegurar contacte metàl·lic i alineament adequats per a l'operació a longituds d'ona tan menudes. A més, l'absorció dielèctrica incrementa notablement a aquestes freqüències. En conseqüència, tant guies metàl·liques buides com línies de transmissió planars convencionals presenten gran atenuació, sent necessari considerar topologies alternatives. Les Gap Waveguides (GWs), basades en una estructura periòdica que introdueix un efecte de Electromagnetic Bandgap, resulten molt adequades ja que no requereixen contacte entre parts metàl·liques i eviten les pèrdues en dielèctrics. No obstant, tot i el potencial de les GWs, diverses barreres impedixen la consolidació i ús universal d'aquesta tecnologia. D'una banda, la complexa topologia de les GWs dificulta el procés de disseny atés que les simulacions d'ona completa consumeixen molt de temps i no existeixen actualment mètodes d'anàlisi i disseny apropiats. D'altra banda, és necessari evidenciar el benefici d'utilitzar GWs mitjançant dispositius GW d'altes prestacions i comparatives adequades amb estructures convencionals. Aquesta tesi presenta diversos mètodes d'anàlisi eficients, models, i tècniques de disseny que permetran la síntesi de dispositius GW sense necessitat d'un coneixement profund d'aquesta tecnologia. Així mateix, es presenten diversos filtres de banda estreta operant en les bandes Ka i V amb altes prestacions, així com una comparativa rigorosa amb la guia rectangular.
Berenguer Verdú, AJ. (2017). Analysis and design of efficient passive components for the millimeter-wave and THz bands [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84004
TESIS

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Compared with conventional measurements from supervisory control and data acquisition (SCADA) system, phasor measurement units (PMUs) provide time-synchronized and direct measurements of phasors. The availability of synchronized phasor measurements can significantly improve power system protection and analysis. This dissertation is specifically committed to using synchronized measurements for estimation of fault locations in transmission systems. Transmission lines are prone to various short-circuit faults. Accurate fault location is critical for rapid power recovery. Chapter 2 proposes a new fault location method based on sparse wide area measurements. One distinguishing feature of this method is its applicability to both transposed and untransposed transmission lines. In addition, the method is developed based on sparse-wide area measurement that may be taken far away from the faulted line. Shunt capacitances of transmission lines are also fully considered by the algorithm. Moreover, when synchronized measurements from multiple buses are available, an optimal estimator can be used to make the most use of measurements, and to detect and identify potential bad measurements. Most of the existing fault location literatures discuss common shunt faults, including single line-to-ground faults, line-to-line faults, line-to-line-to-ground faults, and three-phase faults. However, in addition to common shunt faults, some complex faults may also occur in power systems. Among these complex faults, evolving fault and inter-circuit fault are two typical examples. Chapter 3 extends the method developed in Chapter 2 to deal with evolving faults. The proposed wide-area fault location methods are immune to fault type evolution, and are applicable to both transposed and untransposed lines. Chapter 4 discusses location of inter-circuit faults. Inter-circuit fault is a type of simultaneous fault, and it is the most common simultaneous fault type. Inter-circuit faults between each circuit in a double-circuit line is the most common inter-circuit fault. A fault location method for inter-circuit faults on double-circuit lines are developed and evaluated in Chapter 4. Chapter 5 puts forward a fault location algorithm, which does not require line parameters information, for series-compensated transmission lines. Two-end synchronized voltage and current measurements are utilized. The proposed method is independent of source impedance and fully considers shunt capacitances of transmission lines.

Ces travaux de thèse portent sur la détection de défauts d'isolement dans des lignes de transmission de grandes longueurs. Il s'agit de détecter des défauts non francs liés à l'isolant entre les conducteurs d'un câble de grande longueur qui sont représentés par le paramètre de conductance de fuite. Détecter ces défauts, signes d'un possible futur court-circuit, est un enjeu important mais nécessite une méthode non invasive. Par exemple, dans le cas des câbles de signalisation SNCF, il s'agit de développer une méthode de diagnostic de très faibles conductances de fuite dans les câbles de signalisation le long des voies ferrées compatible avec la circulation des trains. Il faut savoir estimer, à partir de mesures en un seul point du câble, de fortes résistances distribuées sur plusieurs centaines de mètres sans perturber la bande de fréquences du continu à 40 kHz, réservée aux signaux de service. En effet, les câbles de signalisation de la SNCF qui nous intéressent ont une longueur moyenne de 1500 m et sont utilisés dans la bande de fréquence 0-40 kHz. Nous proposons donc une méthode fréquentielle permettant d'estimer de faibles défauts à moyenne fréquence dans des lignes de transmission uniformes avec pertes. Elle repose sur deux idées principales : une analyse fine des effets conjoints de la dissipation et de la dispersion et une méthode de comparaison de deux lignes ayant les mêmes caractéristiques et ne différant que du paramètre de conductance de fuite. Cette méthode de comparaison a été généralisée dans le cas de lignes multiconducteurs en adoptant une démarche statistique.\\Cette thèse a apporté de nouveaux résultats : des formules d'estimation de pertes découlant de l'analyse fine d'une part des effets conjoints de la dissipation et de la dispersion et d'autre part de la méthode de comparaison de deux lignes. Des simulations numériques ont été faites dans les deux cas afin de valider la méthode fréquentielle proposée. Des expériences ont été réalisées afin de valider l'analyse statistique développée dans le cas de lignes multiconducteurs
This thesis work focuses on the detection of insulation faults in very long transmission lines. This is detecting soft defects related to the insulation between the conductors of a long cable which are represented by the leakage conductance parameter. Detect these faults, signs of a possible future short-circuit, is an important issue but requires a noninvasive method. For example, in the case of railway signaling cables, it is to develop a method of diagnosis of very low leakage conductances in signaling cables along railways compatible with the movement of trains. Be aware estimate from measurements in one point of the cable, strong resistance distributed over several hundred meters without disturbing the continuous frequency range to 40 kHz, reserved for service signals. Indeed, the signal cables from the train that interest us have an average length 1500 m and are used in the frequency band 0-40 kHz.We propose so a frequency method for estimating low defects to medium frequency in uniform transmission lines with losses. It is based on two main ideas : a detailed analysis of joint effects of dissipation and dispersion and a method of comparing two lines having the same characteristics and differing only leak conductance parameter. This method of comparison was widespread in the case of multiconductor lines by adopting a statistical approach.This thesis has brought new results : losses estimation formulas resulting from the detailed analysis of a share of joint effects of dissipation and dispersion and also the method of comparing two lines. Numerical simulations were made in both cases to validate the proposed frequency method. Experiments were performed to validate the statistical analysis in the case of multiconductor lines

La détection des défauts non francs est un passage obligé dans la gestion de la maintenance des câbles (Wire Health Monitoring) et permet d’anticiper l’apparition de défauts francs engendrés par l'aggravation de défauts non francs. Ces travaux de thèse visent à étudier la problématique de défauts non francs dans les câbles électriques. L'étude proposée consiste à étudier le problème direct : modélisation électromagnétique et compréhension des phénomènes physiques liés à la présence des défauts non francs, et impact des défauts sur leurs signatures obtenues par réflectométrie. Il est proposé dans ce travail de caractériser des défauts non francs représentatifs de situations réelles, ce qui peut servir ultérieurement dans la résolution du problème inverse : déterminer la localisation et la sévérité des défauts à partir du réflectogramme en vue du diagnostic. L'approche proposée se fait en deux temps. Dans un premier temps, une caractérisation électromagnétique d’une zone localisée d’un câble présentant un défaut non franc est réalisée grâce à une modélisation électromagnétique prenant en compte la géométrie tridimensionnelle du défaut. Deux méthodes numériques ont été exploitées : une méthode de différences finies dans le domaine temporel (FDTD) et une méthode de Galerkin discontinu. Les résultats des simulations permettent d'exprimer les perturbations engendrées par le défaut et de déduire leur influence sur la propagation des signaux dans le câble. Des validations expérimentales menées dans le domaine temporel et le domaine fréquentiel permettent de confronter les mesures aux prédictions numériques. Dans un deuxième temps, des modèles électriques de défauts sont exprimés sous forme de paramètres localisés R, L, C, et G qui peuvent être utilisés dans un modèle de ligne de transmission. Une telle analyse des défauts non francs permet de relier une faible variation locale des caractéristiques physiques et électriques de la ligne à une variation des signaux de réflectométrie et des paramètres électriques de la ligne. L’approche permet de fournir des informations utiles pour caractériser des défauts et peut ainsi contribuer à améliorer les performances des systèmes de détection
The soft fault detection feature is certainly a very important aspect of wire health monitoring and an important process required in electrical wiring system operation. It has a great influence on the security and quality of supply. In transmission line networks, this feature is needed to provide a timely identification of the faulted line thus anticipating the appearance of severe faults that are initially caused by soft fault degradation. This work focuses on soft fault problems in electrical fault diagnosis and their weak impact on coaxial transmission lines. The objective of this work is to carry out a soft fault forward model: electromagnetic modeling and investigating the behavior of the line after soft damages and then to analyze its effects on their signatures obtained by reflectometry. It is proposed in this work to characterize the representative soft damages in real situations, which could be used later in solving the inverse problem: determining the position and severity of defects from the reflectometry response for the diagnosis. The proposed approach is based on the following steps: first, an electromagnetic characterization of a faulty region of a cable is carried out by electromagnetic modeling, by taking into account the three-dimensional geometry of defect. For this purpose, two numerical methods have been used: Finite Difference Time Domain (FDTD) and a Discontinuous Galerkin. The simulation results allow to study the disruption initiated by the fault and to infer their influence on the signal propagation along the cable. The experimental validation provided in frequency- and time-domain allows to confront experimental measurements with simulation predictions. In a second step, electrical fault models are expressed in terms of lumped parameters R, L, C, and G, which can be used in a transmission line model. Such analysis of soft faults allows to relate low local variation of the physical and electrical characteristics of the line to a reflectometry signals variation and electrical parameters changes. The approach can provide useful information to characterize defects and can thus contribute to improve the performance of detection systems

Este trabalho tem o objetivo de apresentar o desenvolvimento de uma metodologia para a proteção de retaguarda de linhas de transmissão de grandes áreas, utilizando dados de um Sistema de Medição Fasorial Sincronizada. O estudo se justifica devido à contínua expansão dos Sistemas de Transmissão, tais como os que fazem parte do Sistema Interligado Nacional. Vale esclarecer que esta expansão pode vir a dificultar a operação e controle do mesmo, o que faz com que seja necessário, um sistema de proteção cada vez mais confiável, que diminua o impacto de eventos danosos de grande porte, e que atenda aos requisitos de um sistema de proteção de grandes áreas. Neste contexto, o modelo do sistema elétrico de potência em análise foi implementado computacionalmente a partir do RSCAD, ambiente computacional e interface gráfica do RTDS® (Real Time Digital Simulator). Como principal passo, o algoritmo desenvolvido verifica a variação da potência ativa em todos os barramentos monitorados do sistema de transmissão e, de acordo com tal variação, associada ao estado dos dois extremos da linha, detecta e aponta a localização de uma situação de falta. Pelos resultados obtidos, a metodologia se mostrou eficiente na detecção e localização da falta em linhas de transmissão para sistemas de grandes áreas. Toda a metodologia desenvolvida, considerações adotadas e os promissores resultados observados serão reportados neste documento.
This work aims to present the development of a methodology for wide area transmission line backup protection, using Synchronized Phasor Measurement Systems. This study is justified due to continuous expansion of Transmission Systems, such as those which are part of the National Interconnected System. It is worth clarifying that this expansion might difficult system operation and control, which makes necessary to have an increasingly reliable protection system, that minimizes the impact of large dangerous events, and, at the same time, supplies the requirements of a wide area protection system. Within this context, the electrical system model under analysis was implemented through RSCAD, which is a RTDS® (Real Time Digital Simulator) computing environment and graphical interface. As main step, the developed algorithm verifies the active power variation in all monitored buses of the transmission system and then, according to such variation, associated with the communication of the variation state of both line sides, detects and indicates the localization of a faulting condition. According to the results obtained, the methodology has shown its efficiency in transmission line faults detection and localization for wide areas of electrical power systems. The entire developed methodology, considerations adopted and promising outcomes will be reported along this document.

As exemplified by sensory illusions, perception is interpretative rather than faithfully representational of the changes in the world. All perceptual pathways involve stimulus transduction, transmission, and modulation before sensory events are coded by the nervous system. The set of stimuli that humans respond to are a subset of the stimuli that elicit reactions across the animal kingdom. The brain processes visual, auditory, mechanical, and vestibular stimuli by breaking stimuli into their sinusoidal components for neuronal processing. The probabilistic response of sensory receptors to stimulation within a receptive field is described. A fundamental property of sensory perception is responsiveness to a wide range of stimulus intensities over several orders of magnitude. Yet, at any one time, the response to a stimulus is proportional to the background level of stimulation. The concept of labeled line sensory transmission is described, and the reality of multimodal integration is revealed through examples.

The most important influence shaping the religious and spiritual lives of children, youth, and teenagers is parents. Yet little research has studied this link in the intergenerational transmission of religion between generations. This book reports the findings of a new, national study of religious parents in the United States. The findings are based on 215 in-depth, personal interviews with religious parents from many traditions and different parts of the country; and on analyses of two nationally representative surveys of American parents. Unlike many studies that focus only on mainstream Christianity, this book reports on parents from a wide range of traditions: mainline Protestant, Catholic, evangelical, black Protestant, Jewish, Muslim, Mormon, Buddhist, and Hindu. It explores the background beliefs informing how and why religious parents seek to pass on religion to their children; examines how parenting styles interact with parent religiousness to shape religious transmission; shows how the approaches of parents now were influenced by their own experiences as children growing up under their parents; reveals how religious parents view their congregations and what they most seek out in a local church, synagogue, temple, or mosque; explores the experiences and outlooks of immigrant parents; and steps back to consider how the field of American religion has transformed over the last 100 years to explain why parents shoulder such a huge responsibility today in transmitting religious faith and practice to children. The book will interest scholars of religion, family, parenting, and socialization; clergy and religious educators and leaders; and religious parents themselves.

The power company has improved the safety of important crossover lines by installing backup clamps to the tensile wire clamps. However, it remains to be studied whether the backup clamp can withstand the impact of the wire tension when it breaks. In this paper, the finite element model of the tension clamp with backup clamp is established and verified the accuracy of the model with an actual line as the engineering background. The results show that the back-up clamp force instantaneously reaches 49501.1N at the moment of tension clamp breakage, and the effectiveness of the back-up clamp is indeed affected. Finally, the effect of the installation height on the impact coefficient is combined to give suggestions to improve the effectiveness of the backup clamp.

The results of comparison of parameters of a classical electric power supply system with an electric power supply system using single-wire wave-guide lines with high frequency, proposed by N. Tesla 100 years ago, are presented. The future world energy model based on direct solar energy conversion and transcontinental terawatt power transmission with the use of resonant wave-guide technology developed by N. Tesla is proposed. The trends of the future development of electric engineering and energy technologies for agriculture, space exploration, solar energy, hydrogen energy, and electric transport based on resonant wave-guide methods of electric power transmission and application are suggested. Substantiation of the use of resonant electric technologies for hydrogen generation by water electrolysis as well as the technical parameters of the plant and the experiment findings are given.

In this paper, a multi-layer LCP substrate fabrication process was described and millimeter wave transmission lines and filters were designed and fabricated on the LCP substrate. Various transitions from a CPW to a microstrip line with their characteristic impedance being 50 ohms were investigated. The characteristics of the wirebonding assembly for connecting two transmission lines was also examined. The measurement results show that an insertion loss of 1.3 dB at 60 GHz can be achieved for the two-wire bonding trasmisssion line including two transitions from a CPW to a microstrip line.

The results of developments to improve the educational and research version of the computer-aided design of overhead power lines of high and ultrahigh voltage are considered. On the basis of the latest proposed version of the structural scheme of the educational and research CAD of overhead lines, as a result of the conducted developments, new calculated ratios for the systematic mechanical calculation of overhead wires (cables) are obtained. Numerical calculations of the parameters of the model of the slack curve of the overhead line wire are performed using various theories. Numerical calculations of the parameters of the wire SAG curve model at a large overhead line transition are performed using various theories.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.