Made available in DSpace on 2014-06-11T19:22:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-25Bitstream added on 2014-06-13T18:49:36Z : No. of bitstreams: 1 torrezan_r_me_bauru.pdf: 1668461 bytes, checksum: ae59290a98e522168089dfc069101ce7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este projeto de pesquisa tem por objetivo apresentar propostas para aprimoramento das principais normas e resoluções envolvidas, dentre as quais o PRODIST, quanto à metodologia para apuração do indicador de distorçõ de tensão harmôica total, bem como trazer contribuições para o processo de análise de compatibilidade de cargas potencialmente perturbadoras na qualidade da energia elétrica em sistemas de distribuição, através de uma visão proativa, ou seja, atuando principalmente no momento que antecede a instalação destas cargas. Estas propostas foram elaboradas a partir da análise e discussão dos resultados obtidos através dos ensaios realizados em um estudo de caso compreendendo a análise de ligação de um novo forno de indução em uma Fundição atendida por uma concessionárias de distribuição do Estado de São Paulo. Um histórico geral situando a qualidade da energia elétrica no setor elétrico é apresentado, as principais normas, resoluções e estudos técnicos são discutidos, e as diretrizes metodológicas e procedimentos utilizados nos ensaios experimentais são detalhados. A análise e discussão dos resultados é elaborada procurando responder às principais perguntas surgidas durante a investigação técnico-científica e a realização dos procedimentos, bem como indicando outros questionamentos a serem estudados, através da apresentação das propostas e indicações para trabalhos futuros / This research project aims to present proposals for improvement of key standards and resolutions involved, among which the PRODIST, on the methodology for calculating the indicator of voltage total harmonic distortion, and should contribute to the analysis process of the potentially disturbance impacts of loads on power quality in distribution system, through a proactive vision, ie, working mainly in the moment before the installation of these loads. Those proposals were developed from the analysis and discussion of results obtained through tests on a case study including analysis of the connection of a new induction furnace in a froundry fed by a distribution utility in the State of São Paulo. A general historical situating the quality of electric energy in the sector is presented, the main standards, technical studies and resolutions are discussed, and methodological guidelines and procedures used in experimental trials are detailed. The analysis and discussion of results is prepared to answer the main questions that arise during the technical-scientific research and implementation of procedures as well as indicating other questions to be studied through the submition of proposals and directions for future work

International Relations theory has paid bare attention to the dynamics of results of crisis between powers operating in different regions. Existing literature shows that when a power is predominant in a region, major war is less likely to take place in that specific region. However, it is not clear whether the rule of predominant stability applies to situations where a major crisis arises between a local power and a geographically distant power. This project argues that two variables, Local Distribution of Power and Dyadic interregional Distribution of Power, determine the Result of Major interregional Crisis (war onset or peaceful resolution). Local Distribution of Power refers to distribution of power among local players and takes on two values: preponderance and non-preponderance. Dyadic interregional Distribution of Power refers to the power balance between the local power and the geographically outside power that confront each other in a major interregional crisis. It takes on three values: outside superiority, local-outside balance and local superiority. A large N analysis is used to test the relationship between the independent variables and the dependent variable. And three longitudinal case studies are used to reveal the causal mechanism between the Dyadic interregional Distribution of Power and the Result of Major interregional Crisis. It is observed that when a major interregional crisis breaks out, a predominant local power distribution and power superiority of the outside power is more likely to end up in war, while a predominant local power distribution and a balanced dyadic interregional power distribution is more likely to lead to peaceful resolution of the crisis. In the former case, the complacent outside power tend to refuse to make concessions, while the local power, dominated by determination, opportunism and perceptions of local advantage, tends to opt for war. Other local players are also motivated to rely on the outside power to challenge the local power, which might entangle the outside power into war. In the latter case, the outside power, given its disadvantage of locality, tend to be cautious and refuse to be entangled by third parties into conflict, while the local power, being confident and aware of the high cost of a war, tend to be assertive but cautious, which contributes to peaceful resolution of the crisis.

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

Over the past decades, the concepts and methods for reliability assessment have evolved from analysing the ability of individual components to operate without faults and as intended during their lifetime, into the comprehensive approaches for evaluating various engineering strategies for system planning, operation and maintenance studies. The conventional reliability assessment procedures now receive different perspectives in different engineering applications and this thesis aims to improve existing approaches by incorporating in the analysis: a) a more detailed and accurate models of LV and MV networks and their reliability equivalents, which are important for the analysis of transmission and sub-transmission networks, b) the variations in characteristics and parameters of LV and MV networks in different areas, specified as “generic” UK/Scottish highly-urban, urban, sub-urban and rural network models, c) the relevant requirements for network reliability performance imposed by Regulators on network operators, d) the actual aggregate load profiles of supplied customers and their correlation with typical daily variations of fault probabilities and repair times of considered network components, and e) some of the expected “smart grid” functionalities, e.g., increased use of network automation and reconfiguration schemes, as well as the higher penetration levels of distributed generation/storage resources. The conventional reliability assessment procedures typically do not include, or only partially include the abovementioned important factors and aspects in the analysis. In order to demonstrate their importance, the analysis presented in the thesis implements both analytical and probabilistic reliability assessment methods in a number of scenarios and study cases with improved and more detailed “generic” LV and MV network models and their reliability equivalents. Their impact on network reliability performance is analysed and quantified in terms of the frequency and duration of long and short supply interruptions (SAIFI and SAIDI), as well as energy not supplied (ENS). This thesis addresses another important aspect of conventional approaches, which often, if not always, provide separate indicators for the assessment of system-based reliability performance and for the assessment of customer-based reliability performance. The presented analysis attempts to more closely relate system reliability performance indicators, which generally correspond to a fictitious “average customer”, to the actual “best-served” and “worst-served” customers in the considered networks. Here, it is shown that a more complex metric than individual reliability indicators should be used for the analysis, as there are different best-served and worst-served customers in terms of the frequency and duration of supply interruptions, as well as amounts of not supplied energy. Finally, the analysis in the thesis considers some aspects of the anticipated transformation of existing networks into the future smart grids, which effectively require to re-evaluate the ways in which network reliability is approached at both planning and operational stages. Smart grids will feature significantly higher penetration levels of variable renewable-based distributed generation technologies (with or without energy storage), as well as the increased operational flexibility, automation and remote control facilities. In this context, the thesis evaluates some of the considered smart grid capabilities and functionalities, showing that improved system reliability performance might result in a deterioration of power quality performance. This is illustrated through the analysis of applied automation, reconfiguration and automatic reclosing/remote switching schemes, which are shown to reduce frequency and duration of long supply interruptions, but will ultimately result in more frequent and/or longer voltage sags and short interruptions. Similarly, distributed generation/storage resources might have strong positive impact on system reliability performance through the reduced power flows in local networks and provision of alternative supply points, even allowing for a fully independent off-grid operation in microgrids, but this may also result in the reduced power quality levels within the microgrids, or elsewhere in the network, e.g. due to a higher number of switching transfers and transients.

Thesis (M.Eng.)--University of Wollongong, School of Electrical, Computer & Telecommunications Engineering. / Typescript. Includes bibliographical references: leaf 143-147.

Thesis (M. En.)--Miami University, Institute of Environmental Sciences, 2004. / Title from first page of PDF document. Includes bibliographical references (p. 31).

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O monitoramento do carregamento de componentes elÃtricos constitui-se em um aspecto de grande importÃncia para qualquer sistema de potÃncia, pois a partir dele podem ser observadas as condiÃÃes de seguranÃa dos seus componentes. O presente trabalho propÃe um mÃtodo computacional baseado em Redes Neurais Artificiais para monitorar o carregamento de componentes elÃtricos do sistema de distribuiÃÃo de energia, como transformadores, alimentadores e linhas de subtransmissÃo. A partir dos dados colhidos dos medidores das subestaÃÃes, contendo os valores de corrente do componente considerado, sÃo realizadas duas anÃlises: com transferÃncia de carga e sem transferÃncia de carga. Desta maneira, objetiva-se determinar os valores mÃximos de corrente nas duas situaÃÃes para o correspondente transformador, alimentador, ou linha de subtransmissÃo analisada. Busca-se entÃo, obter o seu carregamento mÃximo em ambos os casos e a partir desses valores, determinar se o componente està ou nÃo operando em boas condiÃÃes de seguranÃa. O valor mÃximo de corrente com transferÃncia de carga à simples de ser obtido, pois consiste apenas no valor mÃximo dos dados de corrente sem qualquer tipo de anÃlise mais aprofundada. PorÃm, o valor mÃximo de corrente sem transferÃncia de carga à bastante complexo de ser determinado, pois as condiÃÃes atÃpicas dos dados devem ser eliminadas. Desta forma, um mÃtodo empregando Redes Neurais Artificiais foi desenvolvido para obter este valor de corrente para os componentes analisados. Os resultados se mostraram bem prÃximos dos valores reais, comprovando a eficÃcia do mÃtodo. Finalmente, pode ser concluÃdo que o monitoramento à perfeitamente possÃvel de ser realizado, possibilitando um maior controle sobre os carregamentos, evitando danos tanto ao sistema de distribuiÃÃo, como ao sistema de potÃncia como um todo. / The monitoring of the electrical components loading is an aspect of great importance to any power system, since the components safety conditions can be observed from it. The present study proposes a computational method based on Artificial Neural Networks to monitor the electrical components loading of the power distribution system, as transformers, feeders and subtransmission lines. Based on the data collected from the substations meters, containing the electric current values of the considered component, two analyses are done: with load transfer and without load transfer. Thus, the aim is to determine the current maximum values in both situations to the corresponding transformer, feeder, or subtransmission line analyzed. Then it is sought to obtain the maximum loading in both cases and, from these values, to determinate whether or not the component is operating in good safety conditions. The maximum current with load transfer is simple to obtain, because it consists only in the maximum value of electrical current data without any deeper analysis. However, the maximum current without load transfer is very complex to be determined, once the atypical conditions of the data must be eliminated. Thereby, a method using Artificial Neural Networks was developed to estimate the values of the current to the analyzed components. The results were very close to the real ones, proving the effectiveness of the method. Finally, it can be concluded that the monitoring is perfectly possible to be performed, allowing greater control over the loadings, avoiding damages to both the distribution system and the power system as a whole.

Increasing amounts of solar power connected to the low-voltage network will adversely affect the performance of the network. The two impacts that will most often set the limit are overvoltage with the customers and overloading the distribution transformer. In this work, alternative methods have been studied for determining when a transformer is overloaded, to allow more solar power to be connected to the low-voltage network, i.e., increasing the hosting capacity for solar power.A limit-based method on the highest temperature inside the transformer (the hotspot temperature) and a method based on the loss-of-life of the transformer insulation due to hotspot temperatures above the design temperature are those alternative methods in this study. These methods are known as "dynamic transformer rating", a technology proposed in the literature but with very little practical experience in distribution networks.Two models were developed and implemented in MATLAB: a thermal model of the transformer calculating the hotspot temperature for a given time series of loading and ambient temperature; and a model for the loss-of-life of the winding insulation for given time series of the hotspot temperature. These models have been applied to existing distribution networks: measured consumption patterns with high time resolution (10-minute time step) for nine different distribution transformers for 1.5 years (network operator); measured ambient temperature (SMHI); and solar-power production calculated from satellite measurements (Renewables Ninja).For these nine distribution transformers, the time series of the hotspot temperature and the loss-of-life over the 1.5 years have been calculated for different values of the solar power installed capacity on the low-voltage side of the distribution transformer. The resulting time series are used to estimate the hosting capacity for solar power of a 200 kVA transformer. Using the existing design methods, the hosting capacity is 200 kW. Once that value is reached, the further connection of solar power should be stopped until a larger transformer is available. According to IEC design methods, the hosting capacity is about 270 kW using a limit to the hotspot temperature. This value somewhat depends on the loading patterns of the transformer before the connection of solar power. Once that value is reached, the further connection should again be stopped. Even for installed capacity exceeding 270 kW, the loss of life of the transformer insulation is still small and acceptable. This allows for further connection of PV without the immediate need to replace the transformer. Even values up to 350 or 400 kW may be acceptable, but a limit based on loss-of-life will require a detailed risk analysis as the pre-solar loading of the transformer is shown to play an important role.This work has shown that dynamic transformer rating allows more solar power to be connected to a distribution network than using classical rating methods without unacceptable risk for transformer loss-of-life.

Before putting new power distribution installation into operation and before the connection to grid is needed to validate connectivity of the installation. Purpose of verification is to check compliance with the technical conditions of relevant regulations. Ones of the most important conditions include compliance with the prescribed connection voltage tolerance at the connecting device – and even in the worst-case – and provide necessary short-circuit capability of the other devices in a connected grid. Main task of my master’s thesis is just checking that the voltage tolerance and the control of short-circuit resistance. The calculations were performed by using the dispatching control system that works with the current parameters of the distribution system equipment 110 kV. Theoretical part of thesis describes two main points of the method of calculating the network operation and the method of calculating short-circuit conditions. Based on these theoretical processes are relevant input data processed and evaluated in the dispatching control system. The calculation and evaluate results are presented in the final part of the master’s work.

Syftet med uppsatsen var att granska domstolsbeslut om överflyttning av vårdnad, där hovrätten har ändrat tingsrättens ursprungliga dom. Målsättningen var att belysa vilka omständigheter som låg till grund för beslut samt vilka skillnader som fanns mellan tingsrättens och hovrättens bedömningar. Studien genomfördes med hjälp av ett strukturellt maktperspektiv i kombination med ett rättighetsperspektiv. Vi använde oss av en kvalitativ design till vår studie och kvalitativ innehållsanalys för att analysera innehållet i de domstolsbeslut som vi begärde ut. Av resultatet framgick att domstolarna beaktade ett antal specifika omständigheter vid bedömning av överflyttning av vårdnad: barnets anknytning och relation till familjehemmet, vårdnadshavares föräldraförmåga, barnets relation och umgänge till vårdnadshavare, insatser riktade till vårdnadshavare och möjlighet till återförening samt barnets bästa. Under analysen av vårt insamlade material fann vi att det förekom skillnader i hur domstolarna gjorde sin bedömning beträffande de omständigheter som ovan nämnts. Utifrån studiens resultat drogs slutsatser beträffande att domstolarna i stor omfattning beaktade liknande omständigheter inför beslut gällande överflyttning av vårdnad, men att det förekom skillnader i vilken betydelse domstolarna lade vid respektive omständighet. / The purpose of this essay was to examine court decisions regarding transfer of custody, where the Court of appeal had changed the district court's original judgement. Our aim was to illuminate the circumstances on which the courts made decisions and what differences existed between the district court and the Court of appeal. The study was implemented using a structural perspective of power and a perspective of children's rights. Our study was implemented with a qualitative design and we used a qualitative content analysis to examine the context of our requested court decisions. The results presented following circumstances on which the courts made decisions regarding custody transfer; the child's attachment and relationship to the foster family, parenting ability, the child's relationship and association with the guardians, social services contributions to the guardians and possibility of reunion and best interest of the child. During the analysis of our collected material, we found that there were differences in how the courts made their assessments regarding the circumstances that we mentioned earlier. Based on the results of the study, we were able to draw conclusions that the courts to a large extent took into account similar circumstances before deciding on the transfer of custody. However, the result showed differences in what significance they attributed to each circumstance.