Теоретичні основи електротехніки[

The Theory of Electrical Engineering is presented in three parts: the Basic Theories of Steady-State and Transients in Electrical Circuits and the Basic Theory of Electromagnetic Field. For students of electrotechnical specialties of higher educational establishments, as well as for scientific and technical specialists dealing with modern problems in the theory and practice of electric power engineering and electromechanics.Викладено теоретичні основи електротехніки в трьох частинах: теорія стаціонарних процесів в електричних колах, теорія перехідних процесів в електричних колах і теорія електромагнітного поля. Для студентів електротехнічних спеціальностей вищих навчальних закладів, а також для науково-технічних фахівців, що займаються сучасними проблемами в теорії і практиці електроенергетики та електромеханіки

Modelling and analysis of electric arc loads using harmonic domain techniques

Abstract It has been reported that as much as 12% of global electricity production goes into producing artificial light using arc discharge lamps and that global annual production of these lamps may be as much as 1.2 billion units. In the liquid steel production industry, one metric tone of steel demands, on average, 400 kW-hr and in the year 2007, the crude steel output reached 1,343.5 million metric tons. In both instances, engineered electric arcs are present and represent major loads in electrical power systems which require the utmost attention. They observe a highly non-linear behaviour with the capacity to export harmonic distortion and flicker into the power system. Electric arc furnace installations, in particular, are well-known to be sources of dynamic disturbances affecting neighbouring loads. Arc discharge lamps, on aggregate, may exhibit the same perturbing effect. Over the years, the non-linear nature of these loads and their ubiquitous nature have caught the interest of researchers in all corners of the world and from different backgrounds, including this author. The research work reported in this thesis advances current knowledge in the modelling and simulation of electric arcs with particular reference to arc discharge lamps with electromagnetic ballasts and electric arc furnaces with particular reference to operational unbalances and the impact in the installation of ancillary power electronics equipment. In these two quite distinct applications, linked by the presence of engineered electric arcs, the fundamental modelling item is a non-linear differential equation which encapsulates the physic of the electric arc by applying power balance principles. The non-linear differential equation uses the arc conductance as state variable and adapts well to model a wide range of characteristics for which a set of experimental coefficients are available. A fact of perhaps equal relevance is that the non-linear differential equation is amenable to algebraic representations using operational matrices and suitable for carrying out periodic steady-state solutions of electric circuits and systems. The modelling and numerical solution takes place in the harmonic space where all harmonics and cross-couplings between harmonics are explicitly represented. Good application examples are the harmonic domain solution of arc discharge lamps with electromagnetic ballasts and the harmonic domain solution of electric arc furnaces with ancillary power electronics equipment. Building on the experience gained with the representation of the arc discharge lamps with electromagnetic ballasts, the research turns to the representation of the electric arc furnace installation with provisions for reactive power compensation using power electronic control and harmonic filters. This is a three-phase application which comprises several nodes, giving rise a large-scale model of a non-linear system which is solved in the direct frequency domain using a blend of the Newton-Raphson method and the Gauss-Seidel method, achieving robust iterative solution to a very tight tolerance. Both algorithms are implemented in MATLAB code and the raw simulation results which are the harmonic complex conjugated vectors of nodal voltages are used to assess in a rather comprehensive manner the harmonic interactions involved in both kinds of applications

Assessing the contribution of harmonics at the point of common coupling in networks

Abstract: The presence of harmonics in voltage and current waveforms is a result of an increase in use of nonlinear loads in power systems. Utility and end users are in disagreement over who is responsible of polluting the Point of Common Coupling (PCC) and therefore poor power quality. Hence, there is a need for dedicated techniques of analysis to determine the contributions of harmonics between utility and customer...Ph.D. (Electrical and Electronic Engineering Science

Power quality studies in distribution systems involving spectral decomposition

Im Rahmen der Arbeit wurde eine Methode der Spannungsqualitätsanalyse vorgestellt, die zur Untersuchung von Oberschwingungen und Zwischenharmonischen in Verteilungsnetzen besonders geeignet ist. Der zunehmende Einsatz von elektronisch gesteuerten Geräten führt zur Beeinträchtigung der Energiequalität in elektrischen Netzen. Die resultierende Spannungs- und Stromverzerrung kann für empfindliche Einrichtungen gefährlich sein, besonders dann, wenn der Oberschwingungspegel nahe an den Störfestigkeitspegeln der angeschlossenen Betriebsmittel liegt oder diese überschreitet. Die in der Arbeit vorgestellte Methode findet die bezüglich Oberschwingungen und Zwischenharmonischen gefährdetsten Stellen in einem Verteilungssystem heraus. Somit wird eine Vorab-Analyse zur Ergreifung der notwendigen Maßnahmen ermöglicht. Zunächst wurde das Thema Spannungsqualität und ihr Zusammenhang mit der elektromagnetischen Verträglichkeit aus Sicht der Normen und Vorschriften erläutert. Darauf aufbauend wurde eine grundlegende Klassifikation der Spannungsqualitätsereignisse vorgestellt und analysiert. Es wurde festgestellt, dass die Spannungsqualität aus verschiedenen Gründen zunehmend überwacht werden muss - einerseits aufgrund verstärkter Resonanzgefahr durch wachsenden Anteil nichtlinearer Verbraucher bei gleichzeitig sinkenden Anteil ohmscher Lasten und andererseits, da der durch den veränderten Energiemarkt verstärkte Kostendruck die Evaluierung auch unter wirtschaftlichen Gesichtspunkten notwendig macht. Das Konzept eines entsprechend entwickelten Messsystems zur Beurteilung der Spannungsqualität in Verteilungsnetzen wurde vorgestellt. Der Einsatz der verwendeten Beurteilungsalgorithmen stand hierbei im Zentrum des Messsystems, deren flexibler Aufbau sowohl langzeitige Spannungsqualitätsmessungen aber auch Emissionsmessungen an einzelnen Geräten normgerecht ermöglicht. Im Weiteren wurden Modellierungsansätze für elektrische Betriebsmittel sowie sowohl lineare- als auch nicht-lineare Lasten für die Modellierung im FrequenzBereich vorgestellt. Dabei wurde verdeutlicht, dass das Zusammenwirken zwischen der Störquelle - nichtlinearer Last - und der Störsenke - dem Versorgungsnetz - sehr wesentlich für die Genauigkeit der Simulationen ist. Darauf aufbauend wurde eine messungsbasierte Methode vorgeschlagen, um die zu berücksichtigenden Nichtlinearitäten mit Hilfe einer Crossed-Frequency-Admittance-Matrix im Harmonischen-Bereich zu modellieren. Ein Beispiel illustriert detailliert dieses Verfahren, so dass alle Abhängigkeiten und Wechselwirkungen deutlich werden.  Um die in der Arbeit entwickelte Methode sinnvoll durchführen zu können, müssen im Voraus die sensitivsten Knoten in einem Verteilungsnetz gefunden werden. Deshalb wurde als Kern der entwickelten Methode ein Verfahren vorgeschlagen, das auf der internen Struktur des zu analysierenden Netzes basiert. Nachdem die mathematischen Grundlagen dieses spektralen Ansatzes vorgestellt wurden, wurde eine Beispielanalyse am realen Netz durchgeführt um die Eigenschaften dieser qualitativen Methode zu veranschaulichen. Die Untersuchungen zeigten, dass die Methode zur Beurteilung von Spannungsqualität in Verteilungsnetzen wirkungsvoll anwendbar ist und zu besserer Genauigkeit bei Simulationen führt. Durch die Filterungseigenschaft der Spektralanalyse wurde eine bessere Selektivität der Analyse erreicht als bei herkömmlichen Methoden der Spannungsqualitätsanalyse. Das ist besonders bei Verteilungsnetzen von Vorteil, bei denen ungünstige Verhältnisse bezüglich Spannungs– und Stromqualität, hervorgerufen durch niedrige Kurzschlussleistungen und eine Vielzahl von Störquellen in den Verteilungsnetzen, entstehen. &nbsp

Study of responsibilities assignment methods in power quality

Abstract. The present document is a research report on the study of responsibilities assignment in power quality, theme proposed to be carried out as thesis for the degree of Doctor of Philosophy in Electrical Engineering at the National University of Colombia - Bogotá, the doctoral studies have been advised by the Professor Horacio Torres-Sánchez, who works at the National University of Colombia. A doctoral research project was proposed to guide the development of the doctorate. Besides a justification and a theoretical background about the analysis of responsibilities in power quality, the following preliminary objectives were proposed: _ To develop a methodology aimed to establish the responsibilities of different agents involved in a distribution network regarding power quality disturbances. _ Reviewing and studying of analysis tools useful to determine responsibilities of agents connected to a distribution system. Frequency domain, time domain and non-sinusoidal conditions aimed power theories are some of the analytic tools to be considered. _ Study, review and application of deterministic and random modeling and simulation techniques, in order to represent electric systems and power quality disturbances. Deterministic tools have been widely studied and additional efforts will be required just for specific cases. Random tools require the study of random variables, stochastic processes and Monte Carlo simulation techniques. _ Application of the methodology to real cases. This document reports the doctoral research, which was carried out in the National University of Colombia and the Ruhr University of Bochum - Germany. Along this document the main results achieved in the doctoral studies will be listed as well as the accomplishments of the preliminary proposed objectives. In order to introduce the reader to the theme investigated along the doctoral studies, a presentation of the Analysis of responsibilities is made in Chapter 1. In this chapter the conceptual realization of the analysis of responsibilities is described, such realization has been called the Responsibilities Assignment Problem RAP, once it is presented in terms of a problem to be solved, some details are necessary to orientate the finding of a suitable solution. The mentioned problem leads to new matters of discussion like: _ How should the responsibilities be assessed? _ How ought to be assigned the responsibilities? _ For the currently available methods to assess and assign responsibilities, in what manner must be carried out an evaluation to determine their usefulness and suitability? The precedent issues require a direction to facilitate and orientate the evaluation of the reviewed methods and to develop new ones, experimental cases and reference conditions will be proposed as basement for this purpose. Power Quality disturbances can be understood as any deviation from the conditions a customer or a utility needs to satisfy determined energy necessities, such disturbances have been listed and analyzed in technical standards. The analysis of deviations in the quality of the electric power demands the analysis of the electric power itself, an analysis leading to identify and quantify the disturbances in terms of power quantities and electric signals like voltages and currents. In the Chapter 2. A Review of power definitions will be done to provide a frame of reference to decompose power in parts related to the disturbances under consideration in the present thesis. As it was mentioned, reference conditions and experimental setups must be established to allow a comparative and critical revision of any RAP assessing method. Measurements and simulations have been carried out, a description of the setups, the measurements themselves and their usefulness is going to be presented. Simulations have been carried out as well, they shall be described in a similar way in Chapter 3. Once the conceptual foundation has been set already and the technical aspects and experimental cases have been presented too, a review of currently available methods is possible. Several methods shall be investigated, the Critical Impedance Method, the Multi- Point Method and the Harmonic Pollution Method among others, a critical assessment from the technical and conceptual perspective will be carried out, the assessment will yield desirable and undesirable characteristics of each method, which may be used to improve the methods or to develop new ones. This review can be found in Chapter 4. The doctoral research led to the development of a new method to assess responsibilities, the so called Method of Disturbances Interaction MDI, this method will be presented in Chapter 4 as well. Preliminary research results conducted to an improvement proposal for the Multi-Point Method, such improvement will be shown as well. Power quality disturbances evolve and change in time, their behavior cannot always be forecasted easily, the statistical analysis of disturbances is needed. A Statistical analysis procedure of the indicators to assess responsibilities in power quality is presented. The proposed method and the statistical analysis o_er the possibility of an integration of responsibilities assessment in the currently available standards, this part will be found in Chapter 5. Finally, the conclusions extracted from the thesis are presented along with a summary of the reviewed bibliography.El presente documento es un reporte de investigación sobre el estudio de responsabilidades en calidad de potencia eléctrica. Este tema se propuso para ser desarrollado como tesis para adquirir el título de Doctor en Filosofía en Ingeniería - Ingeniería Eléctrica en la Universidad Nacional de Colombia - Bogotá. Los estudios doctorales fueron asesorados por el Profesor Horacio Torres-Sánchez, quien trabaja como profesor en la Universidad Nacional de Colombia. Se propuso un proyecto de investigación doctoral para dirigir el desarrollo de los estudios doctorales. Además de la debida justificación y presentación de los antecedentes teóricos necesarios, los siguientes objetivos preliminares fueron propuestos: _ Desarrollar una metodología orientada a determinar responsabilidades de diferentes agentes presentes en una red de distribución e involucrados en una condición de perturbación estacionaria de calidad de potencia. _ Revisar y estudiar las herramientas de análisis disponibles para determinar responsabilidades de agentes conectados a un sistema de distribución. Teorías de potencia eléctrica definidas en dominio del tiempo, la frecuencia y para condiciones no sinusoidales son algunas de las herramientas analíticas a ser consideradas. _ Estudiar y revisar técnicas de simulación y modelado, tanto determinísticas como aleatorias, para representar sistemas eléctricos y perturbaciones de calidad de potencia. Los métodos determinísticos han sido ampliamente estudiados, de manera que se requerirán esfuerzos adicionales solamente para casos particulares. Las herramientas de simulación estocástica requieren el estudio de variables aleatorias, procesos estocásticos y simulación de Monte Carlo. _ Aplicación de las metodológicas a casos reales. El presente documento presenta la investigación doctoral que fue desarrollada en la Universidad Nacional de Colombia y la Universidad del Ruhr de Bochum - Alemania. A lo largo del documento se enlistan los principales resultados logrados en el doctorado, así como también el cumplimiento de los objetivos propuestos. Análisis de Responsabilidades en el Capítulo 1. En este capítulo se describe la conceptualización del análisis de responsabilides, la cual ha sido llamada Problema de Asignación de Responsabilidades RAP, posteriormente se enlistan algunos requerimientos necesarios para encontrar una solución apropiada. El problema mencionado conduce a nuevos aspectos de discusión como: _ Cómo se deberían evaluar las responsabilidades? _ Cómo deben asignarse las responsabilidades? _ Para poder determinar la validez de los métodos existentes actualmente para evaluar responsabilidades, de qué manera deben evaluarse? Los aspectos anteriores requieren un direccionamiento para facilitar y orientar la evaluación de los métodos revisados y los propuestos, montajes experimentales y condiciones de referencia serían propuestos con este propósito. Las perturbaciones de calidad de potencia pueden entenderse como cualquier desviación de las condiciones que un cliente requiere para satisfacer sus necesidades específicas. El análisis de las desviaciones en la calidad de la potencia eléctrica exige el análisis de la potencia en sí, que serviría para identificar y cuantificar las perturbaciones en términos de cantidades de potencia y señales eléctricas. En el Capítulo 2 se presenta una revisión de las definiciones de potencia, las cuales otorgan un marco de referencia para descomponer la potencia en porciones relacionadas con las perturbaciones estudiadas en esta tesis. Como se mencionó anteriormente, deben establecerse condiciones de referencia y montajes experimentales para permitir una revisión comparativa y crítica de cualquier método disponible para resolver el RAP. En la investigación conducida se desarrollaron mediciones que se describirían en el Capítulo 3. Una vez que los fundamentos conceptuales hayan sido establecidos, así como los experimentos hayan sido presentados, los métodos de evaluación de responsabilidades pueden ser evaluados. Varios métodos serían investigados: el método de la Impedancia Crítica, el método de Mediciones Multi-Punto y el método de Polución Armónica. Una evaluación de carácter crítico, desde las perspectivas técnica y conceptual, sería realizada para cada método. Dicha evaluación proveería características deseables e indeseables de cada método, las cuales servirían para su mejoramiento o para la elaboración de un método novedoso. La evaluación de los métodos se presentaría en el Capítulo 4. La investigación doctoral condujo al desarrollo de un nuevo método para evaluar responsabilidades, el cual fue denominado Método de Interacción de Perturbaciones MDI, en el Capítulo 4 sería descrito. Algunos resultados preliminares relacionados con el mejoramiento del método Multi-Punto se presentarían también. Las perturbaciones de calidad de potencia evolucionan y cambian con el tiempo, de tal manera que su comportamiento no puede ser predicho con facilidad. De acuerdo con lo anterior, es necesario el análisis estadístico de las responsabilidades. En el capítulo 5 se presenta el análisis estadístico de los indicadores propuestos para evaluar responsabilidades. Finalmente se presentan las conclusiones principales de la investigación desarrollada y un resumen general de la bibliografía consultada.Doctorad

An Update on Power Quality

Power quality is an important measure of fitness of electricity networks. With increasing renewable energy generations and usage of power electronics converters, it is important to investigate how these developments will have an impact to existing and future electricity networks. This book hence provides readers with an update of power quality issues in all sections of the network, namely, generation, transmission, distribution and end user, and discusses some practical solutions

Analysis of the Real Energy Consumption of Energy Saving Lamps

[Abstract] Light emitting diode (LED) and compact fluorescent light (CFL) lamps are widely used because they are associated with low energy consumption and a reduced environmental impact. In the present paper, a study of the real consumption of these devices has been carried out. To do this, the active, reactive, distortion and apparent power and electrical efficiency for various lamps have been measured and calculated. The distortions produced in the network provoke the consumed energy to be in the order of 50–75% higher than that which appears in the commercial characteristics. This situation means that for its operation, it is necessary to generate and distribute an amount of energy much higher than that which is declared as the consumption of these lamps, and so far, this amount of energy is neither quantified nor invoiced. Additionally, groups of lamps have also been studied to check whether, when working together on the same network, there is a compensation phenomenon that reduces the negative effects of individual lamps. We have found that this compensation effect does not occur for the type of devices evaluated