Development of reduced-scale tests for HTLS substation connectors

Power distribution networks face the upcoming challenge of managing the increase of power demand predicted worldwide. Power grid capacity is limited by the number of lines deployed and their characteristics, including conductor section, spacing, or number of phases, among others. Building new lines is costly and faces population opposition in many places. Therefore, a new conductor technology designed to upgrade the existing power lines has arisen. This technology, known as High Temperature Low-Sag (HTLS), permits the rise of capacity of existing power lines without modifying the supporting structures. Nowadays, the conductor technology is mature and under commercialization. But, there is the need to design and assess the behaviour of some auxiliary accessories needed to operate power lines equipped with HTLS conductors. Specifically, the substation connector industry is still developing HTLS substation connectors. From all the design process, the validation of the performance of these products is still a milestone. Currently, the tests performed to hardware for power lines are costly in terms of required infrastructures, testing time, power requirements, monetary cost and environmental affectation. Moreover, many of these tests can only be performed in few facilities all around the world. Furthermore, from an industrial scope, there is a growing interest to obtain the data of such tests in onsite industrial laboratories. Thus, this thesis develops a set of reduced-scale tests equivalent to the ones performed on full-scale connectors to validate the performance of the new designs. This thesis also performs a critical review of some of the methodologies that currently are being applied to assess products lifetime, and proposes the use of modern approaches. Concluding, this document aims to develop a series of test procedures that provide data about the validity of the newly required substation connectors designs in a cheaper, faster, and environmentally-friendlier way, whilst allowing to test the connectors in industrial laboratories, which have much less requirements than those of the full-scale test, since the later often require to be carried out in singular and scarce facilities.Las redes de distribución y transmisión de potencia se enfrentan al reto de manejar el incremento de demanda eléctrica previsto mundialmente. La capacidad de la red eléctrica está limitada por el número de líneas instaladas y sus características. Esto incluye, la sección del conductor, espaciado o número de fases, entre otros. La construcción de nuevas líneas es cara y en muchos casos imposible debido a la enorme oposición a la que se enfrentan en muchos lugares del mundo. Por ello, en los últimos años una nueva tecnología de conductores ha empezado a tomar importancia. Estos conectores conocidos como HTLS (alta temperatura baja flecha), permiten el aumento de la capacidad de las líneas eléctricas existentes sin por ello tener que modificar las estructuras que las soportan. Hoy en día, esta tecnología está suficientemente madura para ser comercializada. Sin embargo, existe la necesidad de diseñar y validar el comportamiento de una serie de accesorios auxiliares para líneas eléctricas. Concretamente, la industria de los conectores de subestación está desarrollando sus productos para líneas HTLS. El proceso de validación de estos conectores es aún un hito por alcanzar. Por el momento, los ensayos realizados sobre aparamenta para líneas eléctricas son costosos en términos de infraestructuras necesarias, tiempo de ensayo, potencia requerida, coste económico e impacto medioambiental. Además, muchos de estos ensayos sólo pueden llevarse a cabo en unas pocas instalaciones disponibles en todo el mundo. Por lo tanto, desde un punto de vista industrial, existe un creciente interés en obtener estos datos en laboratorios industriales. Por ello, esta tesis desarrolla un conjunto de ensayos a escala reducida equivalentes con los que hoy en día se realizan a escala real, con el fin de validar el rendimiento de los nuevos diseños de conector. Esta tesis también realiza una revisión crítica de algunas de las metodologías que hoy en día se llevan a cabo para estudiar el envejecimiento de los conectores de subestación. A su vez, propone el uso de metodologías más modernas para realizar dichos estudios. En conclusión, este documento desarrolla una serie de procedimientos de ensayo para validar los diseños de los nuevos desarrollos de conectores de subestación de una manera barata, rápida y respetuosa con el medio ambiente a la vez que permite el ensayo de dichos productos en laboratorios industriales.Postprint (published version

Development of reduced-scale tests for HTLS substation connectors

Power distribution networks face the upcoming challenge of managing the increase of power demand predicted worldwide. Power grid capacity is limited by the number of lines deployed and their characteristics, including conductor section, spacing, or number of phases, among others. Building new lines is costly and faces population opposition in many places. Therefore, a new conductor technology designed to upgrade the existing power lines has arisen. This technology, known as High Temperature Low-Sag (HTLS), permits the rise of capacity of existing power lines without modifying the supporting structures. Nowadays, the conductor technology is mature and under commercialization. But, there is the need to design and assess the behaviour of some auxiliary accessories needed to operate power lines equipped with HTLS conductors. Specifically, the substation connector industry is still developing HTLS substation connectors. From all the design process, the validation of the performance of these products is still a milestone. Currently, the tests performed to hardware for power lines are costly in terms of required infrastructures, testing time, power requirements, monetary cost and environmental affectation. Moreover, many of these tests can only be performed in few facilities all around the world. Furthermore, from an industrial scope, there is a growing interest to obtain the data of such tests in onsite industrial laboratories. Thus, this thesis develops a set of reduced-scale tests equivalent to the ones performed on full-scale connectors to validate the performance of the new designs. This thesis also performs a critical review of some of the methodologies that currently are being applied to assess products lifetime, and proposes the use of modern approaches. Concluding, this document aims to develop a series of test procedures that provide data about the validity of the newly required substation connectors designs in a cheaper, faster, and environmentally-friendlier way, whilst allowing to test the connectors in industrial laboratories, which have much less requirements than those of the full-scale test, since the later often require to be carried out in singular and scarce facilities.Las redes de distribución y transmisión de potencia se enfrentan al reto de manejar el incremento de demanda eléctrica previsto mundialmente. La capacidad de la red eléctrica está limitada por el número de líneas instaladas y sus características. Esto incluye, la sección del conductor, espaciado o número de fases, entre otros. La construcción de nuevas líneas es cara y en muchos casos imposible debido a la enorme oposición a la que se enfrentan en muchos lugares del mundo. Por ello, en los últimos años una nueva tecnología de conductores ha empezado a tomar importancia. Estos conectores conocidos como HTLS (alta temperatura baja flecha), permiten el aumento de la capacidad de las líneas eléctricas existentes sin por ello tener que modificar las estructuras que las soportan. Hoy en día, esta tecnología está suficientemente madura para ser comercializada. Sin embargo, existe la necesidad de diseñar y validar el comportamiento de una serie de accesorios auxiliares para líneas eléctricas. Concretamente, la industria de los conectores de subestación está desarrollando sus productos para líneas HTLS. El proceso de validación de estos conectores es aún un hito por alcanzar. Por el momento, los ensayos realizados sobre aparamenta para líneas eléctricas son costosos en términos de infraestructuras necesarias, tiempo de ensayo, potencia requerida, coste económico e impacto medioambiental. Además, muchos de estos ensayos sólo pueden llevarse a cabo en unas pocas instalaciones disponibles en todo el mundo. Por lo tanto, desde un punto de vista industrial, existe un creciente interés en obtener estos datos en laboratorios industriales. Por ello, esta tesis desarrolla un conjunto de ensayos a escala reducida equivalentes con los que hoy en día se realizan a escala real, con el fin de validar el rendimiento de los nuevos diseños de conector. Esta tesis también realiza una revisión crítica de algunas de las metodologías que hoy en día se llevan a cabo para estudiar el envejecimiento de los conectores de subestación. A su vez, propone el uso de metodologías más modernas para realizar dichos estudios. En conclusión, este documento desarrolla una serie de procedimientos de ensayo para validar los diseños de los nuevos desarrollos de conectores de subestación de una manera barata, rápida y respetuosa con el medio ambiente a la vez que permite el ensayo de dichos productos en laboratorios industriales

Накладные вихретоковые преобразователи: системы возбуждения оптимального электромагнитного поля (обзор)

Development of technical tools with improved metrological and operational characteristics is the actual problem of the eddy current testing. Ensuring the optimal distribution of the electromagnetic excitation field in the testing zone carries out confident detection of the defects and determination of their geometrical parameters by means of eddy current testing. The purpose of the work was to conduct an analysis of scientific and technical information in the field of eddy current testing to study of the use of electromagnetic excitation fields with a priori specified properties, as well as to generalize and systematize the accumulated experience and approaches to conduct theoretical research in this direction.A review of publications in the field of non-destructive electromagnetic testing devoted to the improvement of the excitation systems of eddy current flaw probes was carried out. The authors considered approaches in which a uniform distribution of the electromagnetic field on the control object surface was achieved by linear and non-linear optimal synthesis of excitation systems, provided the immobility of the probe relative to the testing object. Analysis of eddy current probe designs with a homogeneous excitation field created by circular, rectangular tangential and normal coils, as well as by creating a rotational excitation field was carried out. The authors studied designs of the excitation coils of probes with fields of complex configuration characterized by the original fractal geometry which can increase the probability of identifying defects that were not amenable to detection by classical probes.Studies that suggested the formation of optimal configuration fields in a given area using magnetic cores, field concentrators made of conductive materials and specially shaped screens were analyzed. The authors studied approaches to the implementation of the optimal synthesis of excitation systems of probes with uniform sensitivity in the testing zone using surrogate optimization for cases of moving testing objects taking into account the speed effect.The experience, as well as the results of theoretical studies devoted to the problem of designing eddy current probes with uniform sensitivity in the testing zone due to the uniform density distribution of the induced currents flowing in the object were generalized and systematized. As a result, the classification of probes on a number of features that characterize the excitation systems was proposed.Актуальной задачей вихретокового контроля является разработка технических средств с улучшенными метрологическими и эксплуатационными характеристиками. Уверенное обнаружение дефектов и определение их геометрических параметров средствами вихретокового контроля осуществляется при обеспечении оптимального распределения электромагнитного поля возбуждения в зоне контроля. Цель работы заключалась в проведении анализа научно-технической информации в области вихретокового контроля для изучения сведений об использовании электромагнитных полей возбуждения с априори заданными свойствами, а также обобщения, систематизации накопленного опыта и подходов к проведению теоретических исследований в данном направлении.Проведён обзор публикаций в области неразрушающего электромагнитного контроля, посвящённых совершенствованию систем возбуждения преобразователей вихретоковых дефектоскопов. Рассмотрены подходы, в которых однородное распределение электромагнитного поля на поверхности объекта контроля достигается линейным и нелинейным оптимальным синтезом систем возбуждения при условии неподвижности преобразователя относительно объекта контроля. Проведён анализ конструкций вихретоковых преобразователей с однородным полем возбуждения, созданным круговыми, прямоугольными тангенциальными и нормальными катушками, а также за счёт создания вращательного поля возбуждения. Изучались конструкции катушек возбуждения преобразователей с полями сложной конфигурации, характеризующиеся оригинальной фрактальной геометрией, которые позволяют увеличить вероятность выявления дефектов, не поддающихся обнаружению классическими преобразователями.Также проанализированы исследования, в которых предлагается формирование полей оптимальной конфигурации в заданной зоне с применением магнитопроводов, концентраторов поля из проводящих материалов и экранов специальной формы. Изучались подходы к реализации оптимального синтеза систем возбуждения преобразователей с равномерной чувствительностью в зоне контроля с использованием суррогатной оптимизации для случаев движущихся объектов контроля с учётом эффекта скорости. Обобщён и систематизирован опыт, а также результаты теоретических исследований, посвящён-ных проблеме проектирования вихретоковых преобразователей с равномерной чувствительностью в зоне контроля, обусловленной однородным распределением плотности индуцированных токов, протекающих в объекте. Предложена классификация преобразователей по ряду признаков, характеризующих их системы возбуждения

IMPACT OF PLUG-IN ELECTRIC VEHICLES AND WIND GENERATORS ON HARMONIC DISTORTION OF ELECTRIC DISTRIBUTION SYSTEMS

Harmonic distortion on voltages and currents increases with the increased penetration of Plug-in Electric Vehicle (PEV) loads in distribution systems. Wind Generators (WGs), which are source of harmonic currents, have some common harmonic profiles with PEVs. Thus, WGs can be utilized in careful ways to subside the effect of PEVs on harmonic distortion. This work studies the impact of PEVs on harmonic distortions and integration of WGs to reduce it. A decoupled harmonic three-phase unbalanced distribution system model is developed in OpenDSS, where PEVs and WGs are represented by harmonic current loads and sources respectively. The developed model is first used to solve harmonic power flow on IEEE 34-bus distribution system with low, moderate, and high penetration of PEVs, and its impact on current/voltage Total Harmonic Distortions (THDs) is studied. This study shows that the voltage and current THDs could be increased upto 9.5% and 50% respectively, in case of distribution systems with high PEV penetration and these THD values are significantly larger than the limits prescribed by the IEEE standards. Next, carefully sized WGs are selected at different locations in the 34-bus distribution system to demonstrate reduction in the current/voltage THDs. In this work, a framework is also developed to find optimal size of WGs to reduce THDs below prescribed operational limits in distribution circuits with PEV loads. The optimization framework is implemented in MATLAB using Genetic Algorithm, which is interfaced with the harmonic power flow model developed in OpenDSS. The developed framework is used to find optimal size of WGs on the 34-bus distribution system with low, moderate, and high penetration of PEVs, with an objective to reduce voltage/current THD deviations throughout the distribution circuits. With the optimal size of WGs in distribution systems with PEV loads, the current and voltage THDs are reduced below 5% and 7% respectively, which are within the limits prescribed by IEEE

A Perspective on Conventional High-Temperature Superconductors at High Pressure: Methods and Materials

Two hydrogen-rich materials, H$_3$S and LaH$_{10}$, synthesized at megabar pressures, have revolutionized the field of condensed matter physics providing the first glimpse to the solution of the hundred-year-old problem of room temperature superconductivity. The mechanism underlying superconductivity in these exceptional compounds is the conventional electron-phonon coupling. Here we describe recent advances in experimental techniques, superconductivity theory and first-principles computational methods which have made possible these discoveries. This work aims to provide an up-to-date compendium of the available results on superconducting hydrides and explain how the synergy of different methodologies led to extraordinary discoveries in the field. Besides, in an attempt to evidence empirical rules governing superconductivity in binary hydrides under pressure, we discuss general trends in the electronic structure and chemical bonding. The last part of the Review introduces possible strategies to optimize pressure and transition temperatures in conventional superconducting materials as well as future directions in theoretical, computational and experimental research.Comment: 68 pages, 30 figures, Preprint submitted to Physics Report

A NEW FRAMEWORK FOR MATERIAL INFORMATICS AND ITS APPLICATION TOWARD ELECTRIDE-HALIDE MATERIAL SYSTEMS

Despite many years of material exploration, the vast majority of unique crystalline materials remain undiscovered, and these undiscovered materials may offer stronger steels, better catalysts, improved transistors, and many other solutions to urgent societal problems. We therefore need a fast and efficient way of identifying new materials so that society can harness their benefits. To aid in accelerated materials discovery, this dissertation describes a computational framework designed for high-throughput calculations and analyses: the Simulated Materials Ecosystem (Simmate). This software allows users to explore various crystal databases, predict new materials, quickly calculate properties, and share results across analyses. We illustrate Simmate’s functionality through the exploration of an exotic class of materials known as electrides, which have gained considerable attention in recent literature thanks to their applications as superconductors, co-catalysts, and solid-state dopants. This diverse set of applications derives from an electride’s defining property: bare electrons that exist at isolated lattice sites. “Electride electrons” effectively serve as anions, which led us to propose the direct substitution of electrides with other -1 species, namely, halides (F-, Cl-, Br-, I-). Herein, we use Simmate to explore electride-halide systems, understand transitions between such materials, and predict new systems with enhanced material properties. This work ultimately led to the identification of novel ionic conductors, metastable electrides, and new search algorithms for discovering more of the same. Our framework and high-throughput search strategies are highly generalizable and will accelerate the exploration of many different materials beyond our illustrative examples with electride-halide material systems.Doctor of Philosoph

Computational Chemistry in Rational Material Design for Organic Photovoltaics

The acceleration in global population growth, combined with worldwide economic development, have together dramatically increased the demand for energy. This demand has been filled by fossil fuels. The reliance on fossil fuels as a cheap and convenient means of energy is leading to adverse, and perhaps irreversible, ramifications for the entire planet. Many potential alternative energy sources have been explored to alleviate the dependence upon fossil fuels. The use of solar energy as a renewable energy source has been a key area of investigation to many scientists and engineers looking to solve this problem. Among current solar cell design paradigms, organic photovoltaic cell technology shows significant potential due to its potential low cost, flexibility, and manipulability. While scientific research has led to progress in organic photovoltaics, significant issues remain that must be addressed in order for organic photovoltaic cells to become a more feasible option. The purpose of this paper is to expound the crucial role of computational chemistry in novel material discovery and optimization as it pertains to organic photovoltaics

High-throughput search of ternary chalcogenides for p-type transparent electrodes

Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX(2), where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes