Study of the sustainability of electrical power systems: analysis of the causes that generate reactive power

[Abstract] Reactive power is an important parameter in electrical power systems since it affects the efficiency of the system because it is not useful energy. It decreases the power factor of the system and limits the ability of generators to deliver useful power. It is therefore necessary to understand and correctly measure the phenomenon of reactive energy in three-phase systems. In this paper, we analyze reactive power in linear and unbalanced three-phase systems using the Unified Theory of Electrical Power and the Institute of Electrical and Electronics Engineers Standard 1459-2010 (IEEE Std. 1459-2010) to obtain expressions for reactive power in balanced and unbalanced systems and noting that there are terms that exist only for unbalanced systems. Analysis of the measurements carried out led us to identify the existence of two components of reactive power—that due to reactive elements, and that caused by unbalances in the system. Knowing the causes that generate reactive power, it is possible to act more effectively on the problem and therefore achieve a more sustainable generation of electric power and a lower environmental impact

Detection and classification of power quality disturbances based on Hilbert-Huang transform and feed forward neural networks

This paper presents a hybrid detection method and classification Technique based on Hilbert-Huang Transform (HHT) and Feed Forward Neural Networks (FFNNs) to improve the efficient delivery and ensure accurate detection of quality disturbances in the electrical power grids. First, quantities characteristics of power quality disturbances (PQDs) are introduced according its parametrical conditions. Thereafter, a detection and recognition algorithm is used for single and multiple disturbances. Then, a decomposition process and features extraction using Empirical Mode Decompensation (EMD) is conducted for each of these distorted waveforms into Intrinsic Mode Functions (IMFs). Finally, these features are constructed using signal amplitude and frequency and then after fed to one of the powerful Artificial Intelligence Techniques in this field for training, evaluating and testing using (FFNNs) classifier to verify and confirm the effectiveness of the detection methodology

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

Automated Computational Techniques for High-throughput Image Analysis of Skin Structure

Biological image processing and analysis are concerned with enhancing and quantifying features that reflect different pathological states, based on the use of combinations of image processing algorithms. The integration of image processing and analysis techniques to evaluate and assess skin integrity in both human and mouse models is a major theme in this thesis. More specifically, this thesis describes computational systems for high-throughput analysis of skin tissue section images and non-invasive imaging techniques. As the skin is a largest organ in the mammalian body, and is complex in structure, manual quantification and analysis a hard task for the observer to determine an objective result, and furthermore, the analysis is complex in terms of accuracy and time taken. To look at the gross morphology of the skin, I developed high throughput analysis based on an adaptive active contour model to isolate the skin layers and provide quantification methods. This was utilised in a study to evaluate cutaneous morphology in 475 knockout mouse lines provided by the Mouse Genetics Project (MGP) pipeline, that was generated by the Wellcome Trust Sanger Institute (WTSI). This is a major international initiative to provide both functional annotation of the mammalian genome and insight into the genetic basis of disease. I found 53 interesting adipocyte phenotypes, 18 interesting dermal phenotypes and 3 interesting epidermal phenotypes. I also focussed on the analysis of collagen in the dermis of skin images in several ways. For collagen structure analysis, I developed a combined system of Gabor filtering and Fast Fourier Transform FFT. This analysis allowed the detection of subtle changes in collagen organisation. Using similar images, I also measured collagen bundle thickness by computing the maximum frequency of the FFT power spectrum. To assess collagen dynamics, I developed k-means clustering for segmentation based on colour distribution. The use of this approach allowed the measurement of dermal degradation with age and disease, which was not possible by existing means. Obtaining human skin material to facilitate the drug discovery and development process is not an easy task. The manipulation, monitoring and cost of human subjects makes the use of mouse models more suitable for high-throughput screening. Therefore, I have evaluated skin integrity from mouse tissue rather than human skin, however, mouse skin is thinner than human skin and many morphological features are easier to visualise in human skin, which has implications for analysis. Skin moulds can be used to create an impression of the skin surface. Changes in texture of skin can reflect skin conditions. I developed a skin surface structure analysis system to measure the degree of change in texture of the human skin surface. The alterations detected in texture parameters in skin mould impressions reflected changes caused by sun exposure, ageing and many other clinical parameters. I compared my analysis with the existing Beagley-Gibson scoring system to find correlations between automated and manual analysis to inform a decision on the use of optimal methods. By removing subjectivity of manual methods, I was able to develop a robust system to evaluate, for example, damage resulting from UV exposure. My experimental analysis indicated that techniques developed in this thesis were able to analyse both histological samples and skin surface images in high-throughput experiments. They could, therefore, make a contribution to biological image analysis by providing accurate results to help clinical decision making, and facilitate biological laboratory experiments to improve the quality of research in this field, and save time. Overall, my thesis demonstrated that accurate analysis of the skin to gain meaningful biological information requires an automated system that can achieve feature extraction, quantification, analysis and decision making to find interesting phenotypes and abnormalities. This will help the evaluation of the effects of a specific treatment, and answer many biological questions in fields of cosmetic dermatology and drug discovery, and improve our understanding of the genetic basis of disease

Symmetry in Renewable Energy and Power Systems

This book includes original research papers related to renewable energy and power systems in which theoretical or practical issues of symmetry are considered. The book includes contributions on voltage stability analysis in DC networks, optimal dispatch of islanded microgrid systems, reactive power compensation, direct power compensation, optimal location and sizing of photovoltaic sources in DC networks, layout of parabolic trough solar collectors, topologic analysis of high-voltage transmission grids, geometric algebra and power systems, filter design for harmonic current compensation. The contributions included in this book describe the state of the art in this field and shed light on the possibilities that the study of symmetry has in power grids and renewable energy systems

Power Quality

Electrical power is becoming one of the most dominant factors in our society. Power generation, transmission, distribution and usage are undergoing signifi cant changes that will aff ect the electrical quality and performance needs of our 21st century industry. One major aspect of electrical power is its quality and stability – or so called Power Quality. The view on Power Quality did change over the past few years. It seems that Power Quality is becoming a more important term in the academic world dealing with electrical power, and it is becoming more visible in all areas of commerce and industry, because of the ever increasing industry automation using sensitive electrical equipment on one hand and due to the dramatic change of our global electrical infrastructure on the other. For the past century, grid stability was maintained with a limited amount of major generators that have a large amount of rotational inertia. And the rate of change of phase angle is slow. Unfortunately, this does not work anymore with renewable energy sources adding their share to the grid like wind turbines or PV modules. Although the basic idea to use renewable energies is great and will be our path into the next century, it comes with a curse for the power grid as power fl ow stability will suff er. It is not only the source side that is about to change. We have also seen signifi cant changes on the load side as well. Industry is using machines and electrical products such as AC drives or PLCs that are sensitive to the slightest change of power quality, and we at home use more and more electrical products with switching power supplies or starting to plug in our electric cars to charge batt eries. In addition, many of us have begun installing our own distributed generation systems on our rooft ops using the latest solar panels. So we did look for a way to address this severe impact on our distribution network. To match supply and demand, we are about to create a new, intelligent and self-healing electric power infrastructure. The Smart Grid. The basic idea is to maintain the necessary balance between generators and loads on a grid. In other words, to make sure we have a good grid balance at all times. But the key question that you should ask yourself is: Does it also improve Power Quality? Probably not! Further on, the way how Power Quality is measured is going to be changed. Traditionally, each country had its own Power Quality standards and defi ned its own power quality instrument requirements. But more and more international harmonization efforts can be seen. Such as IEC 61000-4-30, which is an excellent standard that ensures that all compliant power quality instruments, regardless of manufacturer, will produce of measurement instruments so that they can also be used in volume applications and even directly embedded into sensitive loads. But work still has to be done. We still use Power Quality standards that have been writt en decades ago and don’t match today’s technology any more, such as fl icker standards that use parameters that have been defi ned by the behavior of 60-watt incandescent light bulbs, which are becoming extinct. Almost all experts are in agreement - although we will see an improvement in metering and control of the power fl ow, Power Quality will suff er. This book will give an overview of how power quality might impact our lives today and tomorrow, introduce new ways to monitor power quality and inform us about interesting possibilities to mitigate power quality problems. Regardless of any enhancements of the power grid, “Power Quality is just compatibility” like my good old friend and teacher Alex McEachern used to say. Power Quality will always remain an economic compromise between supply and load. The power available on the grid must be suffi ciently clean for the loads to operate correctly, and the loads must be suffi ciently strong to tolerate normal disturbances on the grid

Scientific Advances in STEM: From Professor to Students

This book collects the publications of the special Topic Scientific advances in STEM: from Professor to students. The aim is to contribute to the advancement of the Science and Engineering fields and their impact on the industrial sector, which requires a multidisciplinary approach. University generates and transmits knowledge to serve society. Social demands continuously evolve, mainly because of cultural, scientific, and technological development. Researchers must contextualize the subjects they investigate to their application to the local industry and community organizations, frequently using a multidisciplinary point of view, to enhance the progress in a wide variety of fields (aeronautics, automotive, biomedical, electrical and renewable energy, communications, environmental, electronic components, etc.). Most investigations in the fields of science and engineering require the work of multidisciplinary teams, representing a stockpile of research projects in different stages (final year projects, master’s or doctoral studies). In this context, this Topic offers a framework for integrating interdisciplinary research, drawing together experimental and theoretical contributions in a wide variety of fields

Stimulation Paradigms and Transduction Patterns for Optogenetic Intervention of Astrocytes

Gliosis observed in several neurological disorders is associated with neuroinflammation and enhanced astrocytic Ca2+ levels. The inherent multicellular nature of this neuroinflammation poses challenges in deciphering the exact role of astrocytic Ca2+ signaling and whether it leads to the generation and/or exacerbation of neuroinflammation. These challenges are aggravated by the dearth of systematic characterization of a regulated method for eliciting astrocytic Ca2+ increases. The primary goal of this dissertation is to address the lack of a characterized method by studying optogenetics for eliciting astrocytic Ca2+ increases. As part of this analysis, we aim to identify light stimulation paradigms resulting in consistent astrocytic Ca2+ increases and assess optogenetic construct serotypes yielding maximum target cell transduction. Firstly, a novel protocol was devised to perform simultaneous optogenetics and astrocytic Ca2+ imaging in adult murine brain slices. Neocortical astrocytes exhibited synchronous patterns of Ca2+ activity upon light stimulation, drastically different from resting spontaneous activity, and based on the effect of various light paradigms; we identified ix those conducive for robust astrocytic signaling. Secondly, a theoretical model was constructed to study the effect of short and long-term light stimulation of optogenetically-enabled (ChR2-expressing) astrocytes on their Ca2+ spiking activity and basal level. We further investigated how ChR2 gating dynamics, buffering, and coupling coefficient of Ca2+ influence astrocytic activity in a single cell and a network. The response of select variants of ChR2 to varying light stimulation paradigms and key parameters to design future constructs was explored. A preliminary evaluation revealed model similarities to our in situ experimental data. Finally, to facilitate future translational work and eventual comparison to current disease models, astrocytic transduction of various serotypes of an AAV optogenetic construct was assessed in vivo, and the serotype with maximal transduction efficiency was identified. Overall, we identified light stimulation paradigms that lead to repeated robust activation of astrocytes and AAV serotypes with high astrocytic transduction efficiency, thereby verifying that via an analysis of light stimulation paradigms and serotype transduction patterns, optogenetics can be implemented for inducing astrocytic Ca2+ increases in a controlled and tunable manner

Data-Driven Modeling and Prediction for Reservoir Characterization and Simulation Using Seismic and Petrophysical Data Analyses

This study explores the application of data-driven modeling and prediction in reservoir characterization and simulation using seismic and petrophysical data analyses. Different aspects of the application of data-driven modeling methods are studied, which include rock facies classification, seismic attribute analyses, petrophysical properties prediction, seismic facies segmentation, and reservoir dimension reduction. The application of using petrophysical well logs to predict rock facies is explored using different data analytics methods including decision tree, random forest, support vector machine and neural network. Different models are trained from a set of well logs and pre-interpreted rock facies data. Among the compared methods, the random forest method has the best performance in classifying rock facies in the dataset. Seismic attribute values from a 3D seismic survey and petrophysical properties from well logs are collected to explore the relationships between seismic data and well logs. In this study, deep learning neural network models are created to establish the relationships. The results show that a deep learning neural network model with multi-hidden layers is capable to predict porosity values using extracted seismic attribute values. The utilization of a set of seismic attributes improves the model performance in predicting porosity values from seismic data. This study also presents a novel deep learning approach to automatically identify salt bodies directly from seismic images. A wavelet convolutional neural network (Wavelet CNN) model, which combines wavelet transformation analyses with a traditional convolutional neural network (CNN), is developed and demonstrated to increase the accuracy in predicting salt boundaries from seismic images. The Wavelet CNN model outperforms the conventional image recognition techniques, providing higher accuracy, to identify salt bodies from seismic images. Besides, this study evaluates the effect of singular value decomposition (SVD) in dimension reduction of permeability fields during reservoir modeling. Reservoir simulation results show that SVD is valid in the parameterization of the permeability field. The reconstructed permeability fields after SVD processing are good approximations of the original permeability values. This study also evaluates the application of SVD on upscaling for reservoir modeling. Different upscaling schemes are applied on the permeability field, and their performance are evaluated using reservoir simulation