Σε αυτή την διπλωματική εργασία θα γίνει μελέτη της συμπεριφοράς γραμμών διανομής σε καταπονήσεις από κεραυνούς. Οι κεραυνοί αποτελούν ένα φυσικό φαινόμενο με επικίνδυνα αποτελέσματα για την ασφάλεια των ανθρώπων, των κτιρίων και των ηλεκτρικών συστημάτων. Έτσι, κεραυνοί που πλήττουν άμεσα γραμμές διανομής ή γειτονικό σε αυτές έδαφος, είναι υπεύθυνοι για τα σφάλματα που λαμβάνουμε στο ηλεκτρικό σύστημα. Το αποτέλεσμα της πτώσης κεραυνού μπορεί να οδηγήσει σε στιγμιαίο ή μόνιμο σφάλμα. Στιγμιαίο λέγεται αν αυτό “καθαριστεί” από τις διατάξεις προστασίας και το κύκλωμα να ξαναμπεί σε λειτουργία, ενώ το μόνιμο απαιτεί την εξωτερική παρέμβαση από τεχνικούς για την επαναλειτουργία του κυκλώματος. Οι προβλέψεις για την συμπεριφορά των εναερίων γραμμών διανομής εμπεριέχουν πολλές αβεβαιότητες. Mερικές βασικές παράμετροι όπως η πυκνότητα των κεραυνών, που μετριέται με την πυκνότητα των κεραυνών στο έδαφος (GFD), ή ο υπολογισμός του αριθμού των απευθείας πληγμάτων στην γραμμή απέχουν από την πραγματικότητα. Μελετώντας την εργασία αυτή μπορούμε να δώσουμε ακριβείς προβέψεις σφαλμάτων λόγω κεραυνών σε μια γραμμή διανομής. Στο πρώτο μέρος της εργασίας αναφέρεται η οδηγία της ΙΕΕΕ για τη συμπεριφορά των εναέριων γραμμών διανομής ηλεκτρικής ενέργειας έναντι κεραυνών. Σκοπός της είναι να παρουσιάσει εναλλακτικές λύσεις για τη μείωση των βραχυκυκλωμάτων που προκαλούνται από κεραυνό στις εναέριες γραμμές. Συγκεκριμένα θα προσδιοριστεί η συμπεριφορά των εναέριων γραμμών διανομής σε περίπτωση πτώσης κεραυνού (πλήγματα κεραυνών και βραχυκυκλώματα από επαγόμενη τάση), το επίπεδο μόνωσης των γραμμών διανομής, η προστασία των γραμμών διανομής με προστατευτικό αγωγό καθώς επίσης και η προστασία των γραμμών με αλεξικέραυνα. Στο δεύτερο μέρος της εργασίας, θα αναπτυχθεί η καταγραφή σφαλμάτων και βλαβών λόγω πτώσεως κεραυνών στο δίκτυο της Μ.Τ. σε μετασχηματιστές καθώς και στις γραμμές διανομής Μ.Τ. τα τελευταία πέντε χρόνια (2003 – 2008) στην περιοχή της Αχαίας. Επίσης υπολογίζεται αναλυτικά ο αριθμός των θεωριτικών σφαλμάτων που προκείπτουν σύμφωνα με την παραπάνω οδηγία και γίνεται η συσχέτισή τους με τα πραγματικά αποτελέσματα. Τέλος ακολουθούν κάποια ραβδογράμματα για καλύτρερη κατανόηση των αποτελεσμάτων. / This diploma thesis studies the lightning performance of electric power overhead distribution lines. Lightning is a physical phenomenon which usually has dangerous consequences on people or buildings, and it is also the major cause of faults on typical overhead distribution lines. So a lightning that strikes directly to a distribution line, or to the nearby area is responsible for the damage happening to the electric circuit. Lightning usually causes temporary faults on overhead distribution lines. If the fault is cleared by a breaker or a recloser, the circuit may be successfully reclosed. But it can also cause permanent faults by damaging the equipment, which needs external help in order to restore the damage. Estimates of the lightning performance of distribution lines contain many uncertainties. Some of the basics such as lightning intensity measured by ground flash density (GFD), or estimating the number of direct strikes to a distribution line may have significant errors. Often, rough estimates or generally accepted practices are just as effective as detailed calculations. This guide is intended to provide straightforward estimates of lightning-caused faults. To the first part of this project we can find the “IEEE Guide for Improving the Lightning Performance of Electric Power Overhead Distribution Lines” it’s goal is to present alternative solutions for the reduction of the flashovers caused by the lightning strike on overhead distribution lines. Specifically we deal with the lightning performance of the overhead distribution lines during a lightning case (direct strike or induced flashover), the insulation level of distribution lines, the protection of the distribution lines with a shield wire or with arresters. To the second part of this diploma thesis we can find real fault situations that have happened to the middle voltage distribution circuit to the region of Aegio GREECE the last five years (2003-2008). Moreover there is a detailed way of providing the theoretical number of faults according to this guide, after that follows a comparison between experimental and real values as well as some charts for better understanding of the results.

A universalização da energia elétrica, como uma das principais políticas públicas de inclusão social, tem como desafio a escolha de alternativas tecnológicas capazes de conciliar os aspectos de viabilidade técnica e econômica. A Tecnologia cabos para-raios energizados (PRE), objeto de estudo desta tese, se insere neste contexto. Assim, este trabalho consiste na análise de viabilidade do PRE no esquema trifásico, cuja instalação é associada à linha de transmissão 230 kV do sistema de transmissão de Rondônia. São analisados os aspectos de seu desempenho técnico, operacional e econômico. No aspecto técnico é analisado o desempenho do sistema de aterramento quanto à resistência de terra, tensões de toque e de passo, além de análise da queda de tensão, desequilíbrio de tensão e capacidade de carregamento da instalação. A abordagem técnica é aprofundada após análise do desempenho operacional avaliado a partir da classificação das interrupções verificadas em mais de 180 meses de operação do Sistema PRE Rondônia. Em decorrência dessa avaliação, são obtidos índices operacionais de continuidade, analisados comparativamente em relação a outras alternativas tecnológicas, visando analisar a viabilidade da Tecnologia PRE. Uma das constatações resultantes da análise das causas das interrupções indica um elevado impacto das descargas atmosféricas no desempenho do PRE. Este aspecto é extensivamente analisado quanto aos efeitos das descargas diretas e indiretas sobre a instalação, partindo-se de medições de campo nos contrapesos das torres, medições de resistividade do solo e ensaios na cadeia de isoladores do PRE. Simulações são realizadas utilizando-se os programas computacionais ATPDraw, ERM e CDEGS para análise das tensões resultantes de descargas diretas, tensões induzidas por descargas indiretas e cálculo de resistência de terra, respectivamente. São investigados os efeitos de parâmetros importantes no desempenho do sistema frente a descargas atmosféricas e comparados os números de interrupções estimadas e verificadas em campo, partindo-se de um roteiro metodológico minuciosamente detalhado, a fim de permitir a repetição dos procedimentos em situações semelhantes às analisadas neste trabalho. Após uma análise comparativa do desempenho do sistema PRE em relação a outras alternativas convencionais, são estabelecidos índices de referência para o desempenho operacional da Tecnologia PRE e desenvolvida uma análise econômica da implantação dessa tecnologia em Rondônia. / As one of the major public policies of social inclusion, the universalization of electric energy services has as a challenge to choose appropriate technological solutions that combine technical and economic aspects. The energized shield wire line technology (SWL), subject of this thesis, is in this context. This study aims at evaluating the viability of the SWL technology (three-phase scheme) installed on a 230 kV transmission line in the State of Rondônia. The analysis covers its technical, operational, and economic performance. The former aspect considers the performance of the grounding system regarding the ground resistance and step and touch voltages, analysis of voltage drop, voltage unbalance and the load capacity of the installation. The technical issue is deeply held after the analysis of the system operational performance in Rondônia based on the classification of outages considering a period greater than 180 months. The operational indices that result from this evaluation are compared to those corresponding to other technology alternatives in order to evaluate the viability of SWL technology. The analysis of the causes of interruptions reveals that lightning has a significant impact on the SWL performance. Thus, an extensive analysis is carried out regarding the effects of direct and indirect strokes on the SWL, including field measurements (soil resistivity and tower footing resistance) and laboratory tests (determination of the positive and negative critical flashover overvoltages of insulator strings). Simulations are performed using computer programs of proved validity (ATPDraw, ERM, and CDEGS) for the analysis of lightning overvoltages resulting from direct and indirect strokes and for the calculation of ground resistance. The effects of important parameters on the system lightning performance are investigated and the estimated and observed frequencies of interruptions are compared. The applied methodological procedure is described in detail, to allow the method to be used in other cases similar to the situations examined on this study. After a comparative analysis of the performance of the SWL with respect to other conventional alternatives, reference indices for the operational performance of SWL Technology are set and an economic analysis of the SWL technology in Rondônia is carried out.

A universalização da energia elétrica, como uma das principais políticas públicas de inclusão social, tem como desafio a escolha de alternativas tecnológicas capazes de conciliar os aspectos de viabilidade técnica e econômica. A Tecnologia cabos para-raios energizados (PRE), objeto de estudo desta tese, se insere neste contexto. Assim, este trabalho consiste na análise de viabilidade do PRE no esquema trifásico, cuja instalação é associada à linha de transmissão 230 kV do sistema de transmissão de Rondônia. São analisados os aspectos de seu desempenho técnico, operacional e econômico. No aspecto técnico é analisado o desempenho do sistema de aterramento quanto à resistência de terra, tensões de toque e de passo, além de análise da queda de tensão, desequilíbrio de tensão e capacidade de carregamento da instalação. A abordagem técnica é aprofundada após análise do desempenho operacional avaliado a partir da classificação das interrupções verificadas em mais de 180 meses de operação do Sistema PRE Rondônia. Em decorrência dessa avaliação, são obtidos índices operacionais de continuidade, analisados comparativamente em relação a outras alternativas tecnológicas, visando analisar a viabilidade da Tecnologia PRE. Uma das constatações resultantes da análise das causas das interrupções indica um elevado impacto das descargas atmosféricas no desempenho do PRE. Este aspecto é extensivamente analisado quanto aos efeitos das descargas diretas e indiretas sobre a instalação, partindo-se de medições de campo nos contrapesos das torres, medições de resistividade do solo e ensaios na cadeia de isoladores do PRE. Simulações são realizadas utilizando-se os programas computacionais ATPDraw, ERM e CDEGS para análise das tensões resultantes de descargas diretas, tensões induzidas por descargas indiretas e cálculo de resistência de terra, respectivamente. São investigados os efeitos de parâmetros importantes no desempenho do sistema frente a descargas atmosféricas e comparados os números de interrupções estimadas e verificadas em campo, partindo-se de um roteiro metodológico minuciosamente detalhado, a fim de permitir a repetição dos procedimentos em situações semelhantes às analisadas neste trabalho. Após uma análise comparativa do desempenho do sistema PRE em relação a outras alternativas convencionais, são estabelecidos índices de referência para o desempenho operacional da Tecnologia PRE e desenvolvida uma análise econômica da implantação dessa tecnologia em Rondônia. / As one of the major public policies of social inclusion, the universalization of electric energy services has as a challenge to choose appropriate technological solutions that combine technical and economic aspects. The energized shield wire line technology (SWL), subject of this thesis, is in this context. This study aims at evaluating the viability of the SWL technology (three-phase scheme) installed on a 230 kV transmission line in the State of Rondônia. The analysis covers its technical, operational, and economic performance. The former aspect considers the performance of the grounding system regarding the ground resistance and step and touch voltages, analysis of voltage drop, voltage unbalance and the load capacity of the installation. The technical issue is deeply held after the analysis of the system operational performance in Rondônia based on the classification of outages considering a period greater than 180 months. The operational indices that result from this evaluation are compared to those corresponding to other technology alternatives in order to evaluate the viability of SWL technology. The analysis of the causes of interruptions reveals that lightning has a significant impact on the SWL performance. Thus, an extensive analysis is carried out regarding the effects of direct and indirect strokes on the SWL, including field measurements (soil resistivity and tower footing resistance) and laboratory tests (determination of the positive and negative critical flashover overvoltages of insulator strings). Simulations are performed using computer programs of proved validity (ATPDraw, ERM, and CDEGS) for the analysis of lightning overvoltages resulting from direct and indirect strokes and for the calculation of ground resistance. The effects of important parameters on the system lightning performance are investigated and the estimated and observed frequencies of interruptions are compared. The applied methodological procedure is described in detail, to allow the method to be used in other cases similar to the situations examined on this study. After a comparative analysis of the performance of the SWL with respect to other conventional alternatives, reference indices for the operational performance of SWL Technology are set and an economic analysis of the SWL technology in Rondônia is carried out.