No Brasil, a necessidade crescente por sistemas de geração solar fotovoltaica conectados à rede de distribuição levou ao desenvolvimento de normas brasileiras para a conformidade de inversores. Assim, de forma a atender a população em geral, foi publicada a Portaria 357, de 01 de agosto de 2014, do Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), que inclui inversores para conexão à rede de potência nominal até 10 kW no Programa Brasileiro de Etiquetagem (PBE). Por possuir os equipamentos necessários para a realização dos ensaios de conformidade com a portaria 357, o Laboratório de Sistemas Fotovoltaicos (LSF) do Instituto de Energia e Ambiente da Universidade de São Paulo passa então a ser o primeiro laboratório acreditado pelo INMETRO para a realização desses ensaios. Este trabalho tem como objetivo resumir as experiências de aplicação das normas brasileiras no ensaio de inversores para o PBE no LSF, sendo levantados os resultados obtidos no ensaio de 15 inversores ao longo de três anos de operação da bancada de ensaio para sistemas conectados à rede. A partir deste levantamento conclui-se que, embora as normas brasileiras exijam rigor em seus requisitos, existem inversores capazes de atender aos requisitos normativos brasileiros, assim como existem inversores que necessitam de implementações nos respectivos firmware de controle para conseguirem atender todos os requisitos. Uma vez que as normas brasileiras são recentes, este trabalho também destaca pontos das normas que se beneficiariam de adequações no corpo do texto, a fim de melhorar as rotinas de ensaios em inversores e critérios de conformidade. / In Brazil, the increasing demand for grid-tie photovoltaic systems lead to the development of the Brazilian standards for inverter quality and evaluation. In order to meet the general population demand, the National Institute for Metrology, Quality and Technology (INMETRO) published the normative nº 357 01/08/2014 to include inverters up to 10 kW in the Brazilian Labeling Program (PBE). For having all the equipment needed for inverter conformity evaluation in accordance with the normative nº 357, the Laboratory of Photovoltaic Systems (LSF) of the Institute of Energy and Environment of the University of Sao Paulo becomes the first INMETRO accredited laboratory for conducting the inverter evaluation in Brazil. This works main goal is to summarize the experience acquired for the appliance of the Brazilian standards for inverter testing in the LSF. The results obtained for the test of 15 different inverters during the first three years operating the inverter test bench are showed. Using the data shown this work concludes that, although the Brazilian standards are rigorous on its criteria, there are inverters capable of complying with the standards requirements and there are inverters that need further software and hardware development in order to comply with all the requirements. Since the Brazilian standards are in its first version, this work also aims to point out aspects of the standard that would benefit from text revising in order to improve the test conditions and conformity criteria.

A matriz energética mundial é composta por várias fontes primárias, dentre as quais os combustíveis fósseis, como o petróleo, prevalecem sobre as demais. No entanto, devido ao crescimento populacional e ao desenvolvimento tecnológico e industrial, haverá um conseqüente aumento na demanda de energia e devido à preocupação ambiental, será necessária a busca por outras fontes energéticas. Dentre essas, destaca-se a energia solar fotovoltaica, por possibilitar a geração de forma limpa e descentralizada. O Brasil tem a vantagem de estar localizado na zona inter-tropical, registrando altos índices de irradiação solar durante todo o ano, em comparação com outros países do mundo que já fazem uso desta tecnologia. Neste trabalho, foi estudada a inserção de sistemas fotovoltaicos conectados à rede elétrica pública e integrados em edificações residenciais urbanas. Para tanto, foram dimensionados sistemas para três residências situadas em diferentes regiões brasileiras, e que possuem as mesmas características construtivas e o mesmo consumo médio mensal de energia elétrica. Uma das premissas consideradas foi a autossuficiência energética das edificações apenas utilizando o recurso solar como fonte de geração. As cidades escolhidas para a análise foram Porto União/SC, São Carlos/SP e Petrolina/PE por possuírem diferenças significativas nos níveis de irradiação solar, representando desta forma os extremos encontrados no território brasileiro. A partir do dimensionamento foram estimadas a geração de energia elétrica anual para cada localidade e as curvas de geração foram confrontadas com as curvas de demanda diária média das regiões Sul, Sudeste e Nordeste, representando respectivamente, as três cidades escolhidas. Foram estimados os custos de instalação dos três sistemas, sendo feita ainda uma análise econômica simplificada para a verificação do impacto gerado pela inserção da tecnologia solar fotovoltaica como fonte alternativa na geração de energia elétrica em edificações residenciais urbanas. Para a avaliação econômica foi considerada a adoção do Sistema de Compensação Energética e um Período de Retorno Simples, que é a relação obtida entre o investimento feito inicialmente para a instalação de um sistema fotovoltaico e a economia anual proporcionada por essa instalação. Considerando um período de vida útil de um sistema fotovoltaico como sendo estimado em 25 anos, os resultados demonstraram que todos os sistemas seriam pagos antes desse período. A partir dos dimensionamentos, foi possível concluir ainda que a área requerida para a instalação de sistemas fotovoltaicos em residências é muito pequena e possui elevado potencial de aproveitamento, viabilizando desse modo a sua inserção no ambiente urbano. / The world\'s energy matrix is made up of several primary sources among which fossil fuels, mainly oil, prevail. Nevertheless, given population growth coupled with technological and industrial development, there will consequently be an increase in energy demands and, due to environmental concerns, looking for other energy sources is necessary. Among those, photovoltaic solar energy stands out for providing clean, decentralized energy generation. Brazil has the advantage of being located within the intertropical zone, registering higher levels of solar irradiation throughout the year compared to other countries that already use such technology. In this thesis, we studied the insertion of photovoltaic systems into the public grid and integrated to urban residential buildings. For such, we sized systems for three home environments situated in different Brazilian regions with similar building characteristics and same average monthly consumption. One of the premises considered was the buildings energy self-sufficiency based on solar resources alone. The cities chosen for the experiment were Porto União/SC, São Carlos/SP and Petrolina/PE given their significantly different exposure to solar irradiation, thus representing the extremes found in the Brazilian territory. From the initial sizing up the annual electricity demand for each location was estimated and generation curves were confronted with the daily demand curves from the South, Southeast and Northeast regions representing, respectively, the three chosen cities. Implementation costs were estimated for the three systems along with a simplified economic analysis in order to verify the impact caused by the insertion of photovoltaic solar energy as an alternative source of power generation in urban residential buildings. For the economic evaluation was considered the use of the Compensation System Energy and a Simple Payback Period, which is the ratio between the initial investment for the installation of a photovoltaic system and the annual savings provided by this facility. Considering a life cycle of a photovoltaic system as estimated at 25 years, the results showed that all systems would be paid before that period. From the sizing was still possible to conclude that the area required for the installation of photovoltaic systems in residences is very small and has a high potential for use, thereby enabling their integration into the urban environment

Este trabalho utiliza a experiência do Laboratório de Sistemas Fotovoltaicos do Instituto de Energia e Ambiente da Universidade de São Paulo (LSF-IEE-USP) para propor meios efetivos para qualificação de recursos humanos, dentro de laboratórios com qualidade reconhecida, com o intuito de aumentar a quantidade de especialistas na área. Para tanto, foi criado um local, na forma de laboratório, denominado Unidade de Capacitação Tecnológica, composto por sistemas fotovoltaicos isolados e conectados à rede e por duas minirredes híbridas de geração de energia (solar, diesel e rede elétrica), com sistemas de monitoramento próprios, que permitem a avaliação de diferentes estratégias de operação de sistemas fotovoltaicos. Tal Unidade foi concebida sob uma perspectiva didática, para possibilitar a apropriação das habilidades técnicas e conhecimentos tecnológicos necessários para: a) atuar nas diversas ocupações demandadas pelo setor (instaladores, projetistas e engenheiros); b) desenvolver pesquisas na área (especializações, mestrados e doutorados); e c) prestar suporte para iniciativas interessadas na aplicação da tecnologia fotovoltaica (ensaios, consultorias e treinamentos). A apresentação da Unidade conta com a descrição dos materiais, ferramentas, instrumentos e procedimentos utilizados para a acreditação dos laboratórios que a compõem, permitindo demonstrar a confiabilidade, credibilidade e universalidade de seus processos, especialmente no que se refere à realização de ensaios de conformidade em equipamentos fotovoltaicos. O trabalho também investiga iniciativas de capacitação que estão sendo realizadas em outras universidades, escolas técnicas e iniciativa privada, para compreender o perfil dos profissionais atuantes no mercado. A ideia é demonstrar o quanto é fundamental a criação de uma forma de certificação ou uma política instrutiva para a capacitação dos profissionais de sistemas fotovoltaicos, de forma a promover as boas práticas e inibir aquelas que comprometam a credibilidade da tecnologia. Esta tese demonstra que laboratórios capacitados, como a Unidade descrita neste trabalho, apresentam os elementos necessários para produção e divulgação de conhecimentos, desenvolvimento de produtos, prestação de serviços e treinamento de profissionais requeridos para a expansão do setor, podendo colaborar para a consolidação da energia fotovoltaica como uma alternativa eficaz e confiável no cenário energético brasileiro. / This work uses the experience of the Photovoltaic Systems Laboratory of the Institute for Energy and Environment of the University of São Paulo (LSF-IEE-USP) to propose effective ways for the qualification of human resources within laboratories with recognized quality, in order to increase the amount of experts. Thus, a site was created in the form of laboratory, named Technology Skills Unit, composed of individual photovoltaic systems and two hybrid power systems (solar, diesel and power grid), with monitoring systems that allows evaluation of different operating of photovoltaic systems. This unit is designed in a didactic perspective to enable the appropriation of technical skills and technological knowledge necessary for: a) act in different occupations demanded by the sector (installers, designers and engineers), b) develop research in the area and c) provide support for initiatives interested in the application of photovoltaic technology. The presentation of the Unit has the description of the materials, tools, instruments and procedures for the accreditation of laboratories that comprise it, allowing demonstrate the reliability, credibility and universality of its processes, especially with regard to the testing of conformity in photovoltaic equipment. This study also investigates training initiatives being undertaken at other universities, technical schools, and private initiative to understand the profile of the professionals working in the market. The idea is to demonstrate how essential is the creation of a form of certification or an instructive policy for the professional of photovoltaic in order to promote good practice and inhibit those that undermine the credibility of technology. This thesis demonstrates that trained laboratory personnel with the structure proposed in this paper and accredited as is described, presents the necessary elements for the dissemination of technical and scientific knowledge required to qualify professionals specializing in photovoltaic applications, and may contribute to the consolidation of photovoltaic solar energy as effective and reliable alternative to the energy scenario that is imposed in Brazil today.

O objetivo desta pesquisa é avaliar os parâmetros urbanísticos que influenciam a forma urbana e, consequentemente, maximizam a geração de energia fotovoltaica, no município de São Paulo, tomando por estudo de caso o bairro Belenzinho, em processo de adensamento e verticalização. A avaliação dos parâmetros urbanísticos foi realizada por meio do software de modelagem tridimensional Rhinoceros®, utilizando dois vértices: inicialmente, foi modelada a variação isolada dos parâmetros urbanísticos, utilizando Rhinoceros® associado aos plug-ins Grasshopper® e Diva®, com a finalidade de identificar os valores dos parâmetros urbanísticos que maximizam as respostas da forma urbana em relação à incidência de radiação solar na cobertura das edificações; em seguida, adicionou-se o algoritmo genético Galapagos, identificando-se a melhor combinação dos valores dos parâmetros urbanísticos quanto à maximização da incidência de radiação solar na cobertura das edificações. As análises mostraram que no cenário morfológico atual, 86% da cobertura das edificações existentes recebem entre 1840 e 1879 kWh/m2.ano de incidência de radiação solar, porém, algumas edificações são prejudicadas com sombreamento causada pelas edificações vizinhas. Quando se objetiva otimizar a geração de energia solar fotovoltaica na cobertura de empreendimentos distribuídos no tecido urbano, valores de coeficiente de aproveitamento 3, quando o máximo permitido é 4, ou valores de coeficiente de aproveitamento 2, quando o máximo permitido é 2, associados a taxas de ocupação de 0,70, mostram-se apropriados. A aplicação do Galapagos indica que o ganho da radiação solar incidente por área total de cobertura, através da simulação da variação combinada dos parâmetros urbanísticos, é, em média, 60% maior quando comparado com o pior cenário da variação isolada dos parâmetros urbanísticos, no cenário com empreendimentos distribuídos. Porém, quando se objetiva otimizar a geração de energia solar fotovoltaica na cobertura de empreendimentos concentrados no tecido urbano, valores de coeficiente de aproveitamento 3 e 4, quando o máximo permitido é 4, associados a taxas de ocupação de 0,40, mostram-se apropriados. O uso do Galapagos indica que o ganho da radiação solar incidente por área total de cobertura, através da simulação da variação combinada dos parâmetros urbanísticos, é, em média, 40% maior quando comparado com o pior cenário da variação isolada dos parâmetros urbanísticos, no cenário com empreendimentos concentrados. Assim, a pesquisa indica que a definição de uma política energética municipal para aproveitamento fotovoltaico na cobertura de edificações passa pela análise da viabilidade de soluções de geração concentradas ou distribuídas no território urbano, o que impacta em diferentes formas de apropriação dessa variável na regulação da ocupação do solo, no que tange à definição de intervalos de valores dos parâmetros urbanísticos, gabarito de altura, assim como no uso do solo. / The present study analyses the parameters of the urban form that conditions the PV power generation capacity in a neighbourhood in São Paulo: Belenzinho, which is in verticalization and densification processes. The urban analysis was modeled with Rhinoceros® 3D software, with two vertices. Initially, the case-study area was modeled based on the isolated variation of the urban parameters, with Rhinoceros® software associated with Grasshopper® and Diva® plug-ins, in order to identify the best and worse urban parameter values, considering the solar radiation incidence on the rooftops of isolated buildings. Then, Galapagos genetic algorithm was applied for the purpose of combining the urban parameters, and identified the most suitable values for better exploitation of solar radiation. The analysis showed that in the current morphological scenario, 86% of the existing buildings rooftops have values of solar radiation between 1840 and 1879 kWh/m2.year, withal, some buildings are affected by shading caused by neighboring buildings. When optimizing the generation of photovoltaic solar energy in the rooftops of buildings distributed in area of this case study, values 3 for floor area ratio, when the maximum allowed is 4, or values 2 for floor area ratio, when the maximum allowed is 2, associated to values 0.70 of building coverage ratio to be appropriate. The study indicates that the gain of incident solar radiation by total coverage area through the simulation of the Galapagos genetic algorithm, represents on average 60% more when compared to the worst scenario of the isolated variation of the urban parameters, in isolated buildings. However, when the objective is to optimize the generation of photovoltaic solar energy in the rooftops of concentrated buildings in area of case study, values 3 and 4 for floor area ratio, when the maximum allowed is 4, associated to values 0.40 of building coverage ratio to be appropriate. The study indicates that the gain of incident solar radiation by total coverage area through the simulation of the Galapagos genetic algorithm, represents on average 40% more when compared to the worst scenario of the isolated variation of the urban parameters, in concentrated buildings. Thus, the definition of a municipal energy policy for photovoltaic application on the top of buildings involves the analysis of the feasibility of more concentrated or distributed generation solutions in the urban territory, and its appropriation of this variable in the land use regulation, in relation to the definition of ranges of values of urban planning parameters, building\'s height and land use.

The thesis attempts to investigate the issues pertaining to design, fabrication and application of real-time adaptive systems for building envelopes, and to answer questions raised by the idea of motion in architecture. The thesis uses the Solar Decathlon Competition as a platform to base all the research and consequently to verify their applications. Photo-voltaic (PV) panels and shading devices are two different components of Georgia Institute of Technology s the Solar Decathlon House, located above the roof, that are based on the concept of Homeostasis or self-regulated optimization. For the PV panels, the objective is to optimize energy production, by controlling their movement to track the changing position of Sun, whereas, the objective for the shading devices is to reduce heating or cooling loads by controlling the position of shading devices, thus controlling direct and diffused heat gains through the roof. To achieve this adaptive feature, it required three layers of operations. First was the design of the mechanics of movement, which tried to achieve the required motion for the PV panels and shading devices by using minimum components and parameters. Second was the design of the individual parts that are consistent with the overall concept of the House. And finally, the third layer is the design of controls that automates the motion of the PV panels and Shading Devices, using a set of sensors that actuate the attached motors. As a final product, there is an attempt to integrate the precision and material efficiency of digital fabrication with the self-regulated optimization of the roof components.

Η ηλιακή ενέργεια αποτελεί μια από τις κύριες Ανανεώσιμες Πηγές Ενέργειας (ΑΠΕ). Μπορεί να αξιοποιηθεί είτε μετατρεπόμενη σε ηλεκτρισμό είτε σε θερμότητα. Για τη μετατροπή της σε ηλεκτρισμό η κύρια τεχνολογία που χρησιμοποιείται είναι η τεχνολογία των φωτοβολταϊκών. Αντίστοιχα, για την μετατροπή της σε θερμότητα χρησιμοποιούνται ευρέως οι τεχνολογίες των επίπεδων θερμικών ηλιακών συλλεκτών και των θερμικών συλλεκτών σωλήνων κενού. Βασικό ζητούμενο και στις δύο περιπτώσεις αποτελεί η μεγιστοποίηση της αποδοτικότητας τους. Μια από τις μεθόδους που μπορεί να χρησιμοποιηθεί για την αύξηση της αποδοτικότητας μιας ηλιακής συσκευής είναι η χρήση ενισχυτικών ανακλαστήρων. Επίσης, στις συνήθεις τεχνολογίες φωτοβολταϊκών που εφαρμόζονται σήμερα, η μείωση της θερμοκρασίας λειτουργίας τους βελτιώνει την απόδοση τους. Η διπλωματική ερευνητική εργασία που ακολουθεί περιλαμβάνει τη συγκριτική μελέτη φωτοβολταϊκών διατάξεων, επίπεδων θερμικών συλλεκτών και συλλεκτών σωλήνων κενού. Μελετήθηκαν συστήματα φωτοβολταϊκών με τη χρήση διαφόρων μεθόδων ψύξης, ενεργητικών και παθητικών. Επίσης μελετήθηκε η αύξηση της αποδιδόμενης ηλεκτρικής ενέργειας των φωτοβολταϊκών με χρήση ενισχυτικών ανακλαστήρων (ημικατοπτρικός ανακλαστήρας, ανακλαστήρας αλουμινίου (ματ), λευκός ανακλαστήρας). Υλοποιήθηκαν συνδυαστικά συστήματα με ταυτόχρονη ψύξη και χρήση ενισχυτικού ανακλαστήρα και μελετήθηκε η συμπεριφορά τους. Ακόμα, μελετήθηκε η αύξηση της αποδιδόμενης θερμικής ενέργειας επίπεδου ηλιακού θερμικού συλλέκτη με προσθήκη ενισχυτικών ανακλαστήρων (καθρέπτης, ανακλαστήρας αλουμινίου και λευκός ανακλαστήρας). Τέλος, κατασκευάστηκε διάταξη θερμικού συλλέκτη σωλήνα κενού με επίπεδη ανακλαστική επιφάνεια. Πραγματοποιήθηκαν πειράματα με την προσθήκη ενισχυτικών ανακλαστήρων (ημικατοπτρικός ανακλαστήρας, ανακλαστήρας αλουμινίου και λευκός ανακλαστήρας) και μελετήθηκε η αύξηση της θερμικής απόδοσης του συλλέκτη. Με βάση τα αποτελέσματα των πειραμάτων, εξάγονται αντίστοιχα συμπεράσματα και παρατίθενται προτάσεις σχετικά με τις διατάξεις αυτές. / Solar energy is one of the main Renewable Energy Sources (RES). It can be utilized by being transformed into electricity or heat. The main technology used to transform solar energy into electricity is photovoltaics. Respectively, flat plate solar thermal collectors and evacuated tube solar thermal collectors are the technologies mostly used to transform solar energy into usable heat. One of the main concerns on both cases, is the maximization of their performance. The use of booster reflectors is one of the methods that can be implemented in order to increase the performance of a solar device. Also, a method to increase the performance of the main photovoltaic technologies used at the moment, is to cool them. The following diploma – research thesis includes the comparative study of photovoltaic systems, flat plate solar thermal collectors and evacuated tube solar thermal collectors. Photovoltaic systems with the use of various cooling methods, active and passive, were studied. The increase of the photovoltaic electrical output using booster reflectors (semi specular, aluminum reflector and white reflector) was also studied. Combined systems were implemented, with simultaneous cooling and usage of booster reflector, and their behavior was observed. In addition, the increase of the thermal output of a flat plate collector by using booster reflectors (mirror, aluminum reflector and white reflector) was studied. Finally, an evacuated tube solar thermal collector system with an embedded reflective surface was implemented. Experiments were carried out with the addition of booster reflectors (semi specular, aluminum reflector and white reflector) and the increase of the collector’s thermal output was measured. Based on the experimental results, conclusions and suggestions are made about these systems.

Η παρούσα διπλωματική εργασία πραγματεύεται την μελέτη, προσομοίωση και κατασκευή διάταξης διασύνδεσης φωτοβολταϊκών συστημάτων δύο βαθμίδων με το δίκτυο της χαμηλής τάσης. Αντικείμενο της εργασίας ήταν η πρώτη βαθμίδα που αναλαμβάνει την ανύψωσης της τάσης, που δίνει στην έξοδο ένα φωτοβολταϊκό πλαίσιο, με σκοπό να συνδεθεί στην επόμενη βαθμίδα, όπου γίνεται η αντιστροφή της τάσης. Το κύκλωμα που μελετήθηκε είναι ένας μετατροπέας ανύψωσης και σταθεροποίησης της τάσης εξόδου και επιλέχθηκε από τη σειρά των μετατροπέων Luo. Συγκεκριμένα έπειτα από μελέτη των τοπολογιών και με βάση τις προδιαγραφές που είχαμε στη παρούσα εργασία έγινε η επιλογή δύο διατάξεων ως οι πιο κατάλληλες για την εφαρμογή. Η διάταξη Re-lift ανύψωσης τάσης και το στοιχειώδες κύκλωμα Υπέρ-Ανύψωσης Τάσης μελετήθηκαν θεωρητικά και έγινε προσομοίωση της λειτουργίας τους με πραγματικά στοιχεία. Με βάση τα αποτελέσματα που λήφθηκαν έγινε σύγκριση των δύο μετατροπέων και επιλέχθηκε η μία εκ των δύο για κατασκευή. Τελικά στο εργαστήριο κατασκευάστηκε το στοιχειώδες κύκλωμα Υπέρ-Ανύψωσης Τάσης και ο έλεγχος της διάταξης έγινε με τη χρήση μικροελεγκτή (dsPIC30F4011). Τα πειραματικά αποτελέσματα επιβεβαίωσαν την θεωρητική ανάλυση που έγινε και την ορθή λειτουργία του κυκλώματος. Ο βαθμός απόδοσης που προέκυψε στις πειραματικές μετρήσεις θεωρείται μάλλον χαμηλός της τάξης του 80% για την εφαρμογή αυτή, καθώς αποτελεί την πρώτη βαθμίδα σε σύστημα δύο βαθμίδων. Η συμπεριφορά όμως και το κέρδος τάσης είναι ικανοποιητικά για εφαρμογές χαμηλής ισχύος. / The present diplomatic work deals with the study, simulation and manufacture of a device for the connection of photovoltaic systems of two stages with the network of low voltage. Object of the work was the first stage that undertakes the elevation of voltage; we receive at the output of a photovoltaic panel, so as to connect it with the next stage, where the voltage is inverted. The circuit that was studied is a converter of elevation and stabilisation of the output voltage was selected from the Luo converters. In particular, after studying the topologies and taking into account the specifications that we had in the present work, two topologies were chosen as the most suitable for the application. The Re-lift converter and the elementary circuit of the superlift converters were studied theoretically and their operation was simulated with real elements. Based on the results that were taken, the two converters were compared and was selected which one of the two to manufacture. Finally the superlift elementary circuit was manufactured in the laboratory and the control of the circuit was done with the use of a microcontroller (dsPIC30F4011). The experimental results confirmed the theoretical analysis and the correct operation of the circuit. The degree of efficiency that resulted in the experimental measurements is considered rather low in the order of 80% for this application, while it constitutes the first stage in a system of two stages. The behaviour however and the voltage transfer gain are satisfactorily for applications of low power

Σε αυτή τη διπλωματική εργασία διερευνούνται οι προδιαγραφές που πρέπει να ικανοποιούνται ώστε να είναι εφικτή η σύνδεση εγκαταστάσεων κατανεμημένης παραγωγής στα δίκτυα διανομής και η εφαρμογή τους σε ένα φωτοβολταϊκό σύστημα που συνδέεται στο δίκτυο χαμηλής τάσης. Στο πρώτο κεφάλαιο γίνεται μια επισκόπηση της παρούσας κατάστασης στην ηλεκτρική ενέργεια και αναλύονται οι λόγοι που οδήγησαν στην ανάπτυξη της κατανεμημένης παραγωγής οι οποίοι συνοψίζονται στους περιορισμούς στην κατασκευή νέων γραμμών μεταφοράς, στην αυξημένη ζήτηση παροχής ηλεκτρικής ενέργειας υψηλής αξιοπιστίας, στην απελευθέρωση της αγοράς ηλεκτρικής ενέργειας, στους προβληματισμούς για τις κλιματικές αλλαγές και στην εξάντληση των ορυκτών καυσίμων. Έπειτα αναλύεται ο ορισμός της κατανεμημένης παραγωγής σύμφωνα με τα διάφορα διεθνή ινστιτούτα ηλεκτρικής ενέργειας και αναπτύσσονται οι τεχνολογίες που περιλαμβάνει οι οποίες διαχωρίζονται σε τεχνολογίες φυσικού καυσίμου (fossil fuel technologies) και σε ανανεώσιμες πηγές ενέργειας. Στις πρώτες περιλαμβάνονται οι μηχανές εσωτερικής καύσης, οι αεριοστροβιλικοί σταθμοί, οι μικροστρόβιλοι ή μικροτουρμπίνες και οι σταθμοί συνδυασμένου κύκλου ενώ στις ανανεώσιμες πηγές ενέργειας περιλαμβάνονται οι ανεμογεννήτριες, τα κύτταρα καυσίμου (fuel cells), οι φωτοβολταϊκές γεννήτριες, τα μικρά υδροηλεκτρικά και οι μονάδες παραγωγής ηλεκτρικής ενέργειας από βιομάζα και φυσικό αέριο. Η λειτουργία ενός ηλεκτρικού δικτύου ελέγχεται από συσκευές προστασίας και ρύθµισης της τάσης, που έχουν σκοπό την παροχή προς τους καταναλωτές ηλεκτρικής ενέργειας αποδεκτής ποιότητας, ελαχιστοποιώντας τον αριθµό των σφαλµάτων και προσφέροντας υψηλό επίπεδο ασφάλειας. Η σύνδεση στο δίκτυο µονάδων κατανεμημένης παραγωγής πρέπει να συµβαδίζει µε αυτές τις γενικές αρχές, ώστε αφενός µεν να µην προκαλούνται ενοχλήσεις στους λοιπούς καταναλωτές και αφετέρου να υπάρχει συµβατότητα µεταξύ του δικτύου διανοµής και των εγκαταστάσεων των παραγωγών. Στο δεύτερο κεφάλαιο αναφέρονται οι προϋποθέσεις που πρέπει να ισχύουν για τη σύνδεση και παράλληλη λειτουργία των εγκαταστάσεων παραγωγής µε τα δίκτυα διανοµής, καθώς και ο απαιτούµενος εξοπλισµός ζεύξης και προστασίας, µε στόχο την αποτελεσµατική αντιµετώπιση της πλειονότητας των περιπτώσεων. Οι τεχνικές προδιαγραφές που περιγράφονται αφορούν στη σύνδεση παραγωγών στο δίκτυο µέσης τάσης (ΜΤ) ή χαµηλής τάσης (ΧΤ). Βασικά κριτήρια και προϋποθέσεις που εξετάζονται προκειµένου να επιτραπεί η σύνδεση νέων εγκαταστάσεων παραγωγής είναι η επάρκεια του δικτύου (γραμμών, μετασχηματιστών κλπ.), η συµβολή στη στάθµη βραχυκύκλωσης, οι αργές µεταβολές της τάσης (µόνιµης κατάστασης), οι ταχείες µεταβολές της τάσης, οι εκποµπές flicker, οι εκπομπές αρμονικών, η διαµόρφωση των προστασιών της διασύνδεσης εγκαταστάσεων-δικτύου και η επίπτωση στη λειτουργία συστηµάτων Τηλεχειρισµού Ακουστικής Συχνότητας (ΤΑΣ). Τα κριτήρια και οι µέθοδοι εξέτασης που περιγράφονται στηρίζονται κατά κύριο λόγο στη σειρά προτύπων 61000 της IEC (International Electrotechnical Commission) και εξασφαλίζουν την ικανοποίηση των απαιτήσεων του ευρωπαϊκού προτύπου ΕΝ 50160 (πρότυπο ΕΛΟΤ ΕΝ 50160 και Οδηγία διανοµής 120 της ΔΕΗ Α.Ε.). Στο τρίτο κεφάλαιο πραγματοποιείται μια μελέτη εφαρμογής των παραπάνω προδιαγραφών σε ένα σύστημα που εξομοιώθηκε με χρήση του προγράμματος PSCAD. Το σύστημα αποτελείται από μια φωτοβολταϊκή συστοιχία μέγιστης ισχύος 4,8 kW, έναν μετατροπέα συνεχούς/εναλλασσόμενης τάσης ή αντιστροφέα (DC to AC converter) που λειτουργεί με τη μέθοδο PWM (Pulse Width Modulation ή διαμόρφωση εύρους παλμού), ένα σύστημα παρακολούθησης του σημείου μέγιστης ισχύος που αποδίδει η συστοιχία (MPPT Maximum Power Point Tracker), ένα μετασχηματιστή 150V/380V για την ανύψωση της τάσης στην έξοδο του αντιστροφέα στα επίπεδα τάσης του δικτύου, ένα δίκτυο χαμηλής τάσης και δύο φορτία RL. Εκτενής αναφορά γίνεται στις εκπομπές αρμονικών που παρουσιάζονται στο σύστημα στην έξοδο του αντιστροφέα. Αρχικά γίνεται μελέτη χωρίς φίλτρο LC στην έξοδο του αντιστροφέα και στη συνέχεια παρατηρούμε τον τρόπο με τον οποίο το φίλτρο LC επιδρά στη μείωση των αρμονικών σε επιτρεπτά πλαίσια. Τέλος διερευνούνται οι διακυμάνσεις τάσης του δικτύου κατά τη ζεύξη του φωτοβολταϊκού συστήματος με το δίκτυο, πραγματοποιείται μια μελέτη του συστήματος σε περίπτωση βραχυκυκλωμάτων και διερευνάται η επίπτωση σε συστήματα τηλεχειρισμού ακουστικής συχνότητας. / -

Στην παρούσα διατριβή αναπτύσσονται κατάλληλα μοντέλα για τις επιμέρους μονάδες φωτοβολταϊκού (ΦΒ) συστήματος συνδεδεμένου στο δίκτυο. Στόχος είναι να αντιμετωπιστούν ταυτόχρονα και αποτελεσματικά οι ιδιαιτερότητές του, που οφείλονται στη συμπεριφορά των διακοπτικών στοιχείων και στα μη γραμμικά χαρακτηριστικά της ΦΒ γεννήτριας και του μετασχηματιστή απομόνωσης. Αναπτύσσονται μέθοδοι που αυξάνουν την ταχύτητα εξομοίωσης. Αυτό επιτυγχάνεται με χρήση αυξητικών μοντέλων για τα μη γραμμικά στοιχεία και αποτελεσματικών αλγορίθμων για την αντιμετώπιση της μεταβλητής τοπολογίας. Τα μοντέλα που παρουσιάζονται μπορούν να χρησιμοποιηθούν για συνδεδεμένα στο δίκτυο ΦΒ συστήματα οποιασδήποτε διάταξης. Μέσω εξομοιώσεων της λειτουργίας ενός οικιακού ΦΒ συστήματος συνδεδεμένου στο δίκτυο διερευνάται η ευαισθησία της αρμονικής παραμόρφωσης τάσεων και ρευμάτων σε μεταβολές παραμέτρων του συστήματος. Στη συνέχεια παρουσιάζεται ένα νέο μοντέλο για τη ροή ενέργειας σε κυκλώματα με μη ημιτονοειδείς κυματομορφές. Το μοντέλο παρέχει μαθηματική περιγραφή μέσω του πολυδιανύσματος της ισχύος, το οποίο γεφυρώνει το χάσμα μεταξύ στιγμιαίας και φαινομένης ισχύος, όπως η μιγαδική ισχύς υπό ημιτονοειδείς συνθήκες. Το πολυδιάνυσμα της ισχύος επιτρέπει συστηματική και ενιαία αντιμετώπιση όλων των περιπτώσεων. Το μοντέλο ροής ενέργειας που παρουσιάζεται περιγράφει τις συνιστώσες ισχύος όχι μόνο ποσοτικά, αλλά και ποιοτικά. Από φυσικής πλευράς βασίζεται στη γενίκευση της έννοιας της αμοιβαίας σύζευξης. Η προσέγγιση που ακολουθείται επιτρέπει την φυσική ερμηνεία όλων των συνιστωσών της ισχύος, οι οποίες συνδέονται με μια αναπαράσταση μέσω ισοδυνάμου κυκλώματος. Οι προϋπάρχουσες μέθοδοι μπορούν να προκύψουν ως ειδικές περιπτώσεις του μοντέλου. Η βαθύτερη κατανόηση των φαινομένων ισχύος που παρέχει θέτει το θεωρητικό υπόβαθρο για την επίλυση πρακτικών προβλημάτων, όπως η αντιστάθμιση. Ακολούθως εξετάζεται η επιλογή του βέλτιστου μεγέθους παθητικών φίλτρων με παράλληλους συντονιζόμενους κλάδους. Η διερεύνηση λαμβάνει υπόψη όχι μόνο πηγές αρμονικών ρευμάτων λόγω μη γραμμικών φορτίων αλλά και την παρουσία προϋπάρχουσας αρμονικής παραμόρφωσης της τάσης. Μέσω αναλυτικής μεθόδου προκύπτουν εκφράσεις κλειστής μορφής για απλοποιημένες περιπτώσεις. Αυτές μπορούν να βοηθήσουν στην κατανόηση της επίδρασης διαφόρων παραμέτρων. Επίσης διαμορφώνεται η γενικότερη περίπτωση του προβλήματος και αντιμετωπίζεται με Γενετικούς Αλγόριθμους. Μέσα από εκτεταμένες εξομοιώσεις για διάφορα επίπεδα αρμονικών τάσης και ρεύματος, διερευνώνται διεξοδικά οι δυνατότητες των παθητικών φίλτρων. Τα πρακτικά συμπεράσματα που προκύπτουν μπορούν να βοηθήσουν στη λήψη αποφάσεων για τον έλεγχο των αρμονικών σε διάφορες εφαρμογές. / In this thesis, appropriate models for the individual components of a grid-connected photovoltaic (PV) system are developed. The aim is to simultaneously and efficiently handle its peculiarities, which are due to the switching action of the switching devices and the nonlinear characteristics of the PV generator and the isolation transformer. Methods that increase simulation speed are developed. This is accomplished by using incremental models for the nonlinear components and efficient algorithms to handle the variable topology. The presented models can be used for grid-connected PV systems of any configuration. Through simulations of the performance of a residential grid-connected PV system the sensitivity of the harmonic distortion of voltages and currents to variations in system parameters is investigated. Next, a novel model for the energy flow in circuits with nonsinusoidal waveforms is presented. This model provides a mathematical description through the power multivector, which bridges the gap between the instantaneous and apparent power, like the complex power does under sinusoidal conditions. The power multivector permits a systematic and uniform treatment of all cases. The presented energy flow model describes power components not only quantitatively but also qualitatively. From a physical perspective it is based on the generalization of the concept of mutual coupling. The approach that is followed permits the physical interpretation of all power components, which are associated with an equivalent circuit representation. Pre-existing methods can be derived as special cases of the model. The deeper understanding of power phenomena it provides sets the theoretical foundation for the solution of practical problems, such as compensation. Next, the optimal sizing of shunt, passive, single-tuned filters is examined. The investigation takes into account not only harmonic current sources due to nonlinear loads but also the presence of background voltage harmonic distortion. Through an analytical approach closed-form expressions are derived for simplified cases. These can help in the comprehension of the influence of various parameters. Moreover, the general case of this problem is formulated and solved using Genetic Algorithms. Through extensive simulations for various current and voltage harmonic levels, the potentialities of these filters are thoroughly investigated. The practical conclusions that are drawn can facilitate decisions regarding harmonic control in various applications.

Long term supporting schemes for photovoltaic (PV) system installation have led to accommodating large numbers of PV systems within load pockets in distribution grids. High penetrations of PV systems can cause new technical challenges, such as voltage rise due to reverse power flow during light load and high PV generation conditions. Therefore, new strategies are required to address the associated challenges. Moreover, due to these changes in distribution grids, a different response behavior of the distribution grid on the transmission side can be expected. Hence, a new equivalent model of distribution grids with high penetration of PV systems is needed to be addressed for future power system studies. The thesis contributions lie in three parts. The first part of the thesis copes with the PV modelling. A non-proprietary PV model of a three-phase, single stage PV system is developed in PSCAD/EMTDC and PowerFactory. Three different reactive power regulation strategies are incorporated into the models and their behavior are investigated in both simulation platforms using a distribution system with PV systems. In the second part of the thesis, the voltage rise problem is remedied by use of reactive power. On the other hand, considering large numbers of PV systems in grids, unnecessary reactive power consumption by PV systems first increases total line losses, and second it may also jeopardize the stability of the network in the case of contingencies in conventional power plants, which supply reactive power. Thus, this thesis investigates and develops the novel schemes to reduce reactive power flows while still keeping voltage within designated limits via three different approaches: decentralized voltage control to the pre-defined set-points developing a coordinated active power dependent (APD) voltage regulation Q(P)using local signals developing a multi-objective coordinated droop-based voltage (DBV) regulation Q(V) using local signals   In the third part of the thesis, furthermore, a gray-box load modeling is used to develop a new static equivalent model of a complex distribution grid with large numbers of PV systems embedded with voltage support schemes. In the proposed model, variations of voltage at the connection point simulate variations of the model’s active and reactive power. This model can simply be integrated intoload-flow programs and replace the complex distribution grid, while still keepingthe overall accuracy high. The thesis results, in conclusion, demonstrate: i) using rms-based simulations in PowerFactory can provide us with quite similar results using the time domain instantaneous values in PSCAD platform; ii) decentralized voltage control to specific set-points through the PV systems in the distribution grid is fundamentally impossible dueto the high level voltage control interaction and directionality among the PV systems; iii) the proposed APD method can regulate the voltage under the steady-state voltagelimit and consume less total reactive power in contrast to the standard characteristicCosφ(P)proposed by German Grid Codes; iv) the proposed optimized DBV method can directly address voltage and successfully regulate it to the upper steady-state voltage limit by causing minimum reactive power consumption as well as line losses; v) it is beneficial to address PV systems as a separate entity in the equivalencing of distribution grids with high density of PV systems. / <p>The Doctoral Degrees issued upon completion of the programme are issued by Comillas Pontifical University, Delft University of Technology and KTH Royal Institute of Technology. The invested degrees are official in Spain, the Netherlands and Sweden, respectively. QC 20141028</p>