M.Sc. / The KaNyaka barrier island system consists of the vegetated KaNyaka and Portuguese Islands, and various partially exposed sandbars. It is situated in south-easternmost Mozambique where it forms a barrier between Maputo Bay in the west and the Indian Ocean in the east. It forms part of the northern most limit of the Maputaland Group, which consists of Pliocene to Holocene sediments. The island system is an example of a compound barrier island since it comprises a stacked succession of several ancient shoreline marine and aeolian sedimentary rock units and sediments, along with various active sedimentary environments. This thesis describe the general geology of the island system, the petrography of the various rock and sedimentary units and provide information on provenance of sediment based on detrital zircon age populations. It also provides several new 14C age dates of shell fossils and calcified rhizoliths. KaNyaka Island consists of two high north-south trending dune cordons along its eastern and western shores, with a low-lying dune-covered area in between. The Western dune cordon consists of aeolian calcareous quartz arenite of the Ridjene Formation unconformably overlain by calcified aeolian dunes of the Alto Pocuane Formation in turn overlain by the unlithified red dunes of the Barreira Vermelha Formation. The core of the Eastern dune cordon consists of the calcareous quartz arenite of the Cabo Inhaca Formation comprised of stacked calcified aeolian dunes, the marine and tidal deposits of the Ponta Mazondue and Ponta Torres formations form the eastern and south-western flanks of the Eastern dune cordon. The formations are overlain by unlithified red to orange sands of the Changana Formation and partially lithified light grey to yellow sands of the Muamuluago Formation. The area between these two dune cordons is covered by low-lying aeolian dunes of the Alto Chumine Formation, ancient sandbar and beach deposits of the Chunhe Formation and both modern and paleo-intertidal flat deposits. Modern sedimentary environments include high-energy beaches, intertidal flats, sand spits, sandbars and aeolian dunes. The presence of aeolian deposits extending below the present sea-level, and marine deposits up to 3m above it, indicates that the KaNyaka barrier island system records a long history of sea-level change. 14C dating of marine and freshwater shell fossils and a rhizolith collected from several of the formations on the KaNyaka barrier island system assist in defining the history of the island with reference to sea-level fluctuations. Results from two freshwater shell fossils in the aeolian Alto Pocuane and Cabo Inhaca Formations indicate that they were deposited and subsequently calcified 47 000 and 30 000 years ago respectively, at times when the sea-level was 40 - 60 m lower than at present. The red sand of the Barreira Vermelha and Changana formation overlying these calcified dunes are suggested to have formed when climate was drier and sea-level even lower, during the Last Glacial Maximum (LGM) around 17 000 years ago. 14C ages on formations overlying the red sand deposits all postdate the Last Glacial Maximum and record sediment deposition of the past 7 000 years when the sea-level was either rather similar or somewhat higher than the present. Detrital zircon age populations, determined by laser ablation inductively coupled mass spectrometry (LA-ICP-MS), indicate that the majority of the sediment building the barrier island system was derived from the Grenvillian (~1100 Ma) and the Pan-African (~500 Ma) orogenic belts situated along the eastern side of Africa. Sediment was probably transported from exposed rock successions of these belts by large rivers like the Zambezi in the north and the Tugela in the south. The sediment was then dispersed along the coast by the south flowing Agulhas Current and northward directed long-shore current. Rivers feeding into Maputo Bay, like the Phongola, Umbeluzi and Incomati, draining the Kaapvaal Craton and Karoo Supergroup provided very little sediment to the barrier island system.

This Master´s thesis deals with problematics of wind powered generators and their use in off-grid systems. In its first chapters aspects of wind as a power source are analyzed. Further on the thesis focuses on individual components of the off-grid systems. Also designing procedures of these systems are presented in the paper. The key parts of the thesis are 3 off-grid wind power system designs, which can be used to power a family house, and their energetical and economical evaluation.

The dissertation studies the nonlinear resonance problems of power systems. Generally speaking, ferroresonance has usually occurred in low-voltage distribution system, especially for potential transformers. Due to the considerable increase of power consumption, the power system is more complex than before. Besides, a number of under-ground cables are used, and transformers¡¦ loss reduce due to improvement of core iron material. These factors could probably result in ferroresnance occurring in extra-high-voltage power system. The dissertation proposed three-phase representation method to analyze unbalance and non-linear system. This method employ magnetically coupled electrical circuit techniques and the original voltage equations can be used without the need for any transformations, which improves significantly computation accuracy. Consequently, it is quite suitable for power system design and incident investigation. Since the traditional d-q-0 model is not well suited for the study of unbalanced faults and requires further transformation, the analytical solution becomes rather complicated and the solutions are still inaccurate. At last we simulated the ferroresonant overvoltages occurring at a nuclear power station in Taiwan in order to investigate the causes and afford mitigation. The simulation results were enough to prove accuracy and practicability of this method.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-02-18T13:57:51Z No. of bitstreams: 1 Henrique Tiggemann_.pdf: 3072800 bytes, checksum: d759a40bb6ab933bb882d6a0d2eb6a92 (MD5) / Made available in DSpace on 2016-02-18T13:57:51Z (GMT). No. of bitstreams: 1 Henrique Tiggemann_.pdf: 3072800 bytes, checksum: d759a40bb6ab933bb882d6a0d2eb6a92 (MD5) Previous issue date: 2015-10-09 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / A busca de novas alternativas para o suprimento de energia elétrica em comunidades isoladas sempre foi um desafio motivacional tanto de âmbito cientifico quanto social. Busca-se uma solução robusta, que consiga suprir a demanda solicitada da melhor forma possível e com o menor impacto ambiental. São apresentados neste trabalho a caracterização e o desenvolvimento de uma microrrede híbrida fotovoltaica, conectada a um simulador de carga experimental com suporte a acesso remoto. A microrrede é constituída de quatro módulos fotovoltaicos de duas tecnologias, mono e multicristalino, totalizando 570 W pico de potência e com capacidade máxima de suprir um conjunto de cargas de até 1 kW em tensão alternada de 220 V. Também faz parte da microrrede um banco de estocagem inicial de energia de 200 Ah com tensão nominal de 24 V, formado por baterias seladas associadas em série/paralelo e um quadro de comando onde fica situado o controlador Arduíno e demais componentes de conversão de energia. Para avaliar a microrrede em dias que o banco de estocagem estiver em nível mínimo, foi utilizada a rede da concessionária simulando uma fonte alternativa de energia, que pode ser pilha combustível, gerador a diesel, etc. Foi observado por meio de medições elétricas obtidas pelo sistema de aquisição que a microrrede está funcionando adequadamente. As cargas conectadas nesta microrrede são alimentadas segundo um perfil de funcionamento preestabelecido no projeto, com consumo diário de 962 Wh. Este perfil foi construído segundo um número de horas diárias para o funcionamento de cada carga da residência, podendo ser modificado pelo usuário visando uma economia de energia. A interrupção das cargas não prioritárias pode ser também realizada a distância. O sistema é monitorado e gerenciado através de um controlador Arduíno, e o acesso remoto realizado através de um computador conectado à rede de dados (internet). Tal acesso remoto permite visualizar o comportamento elétrico e energético da microrrede além de possibilitar a utilização do sistema para experimentos técnicos e implementação de novas ações de controle à distância. A microrrede está instalada no prédio C02 da UNISINOS. / The search for new alternatives for energy supply in island communities has always been a motivational challenge in the scientific and societal context. The aim is a robust solution which is able to meet the demand requested in the best way as possible and with the least environmental impact. Is being presented in this work the characterization and the development of a hybrid photovoltaic microgrid, connected to an experimental load simulator that supports remote access. The microgrid consists of four photovoltaic modules of two technologies, monocrystalline and multicrystalline totaling 570 W peak power and capacity to supply loads of up to 1 kW with alternating voltage of 220 V. Is also part of the microgrid an initial storage power bank of 200 Ah with a nominal voltage of 24 V, consisting of sealed batteries linked in series / parallel, and a control panel where the Arduino controller is located and other power conversion components. To assess the microgrid in days of the storage bank is at minimum, the power line grid was used to simulate an alternative source of energy, which can be fuel cell, diesel generator, etc. Has been observed through electrical measurements obtained by the acquisition system that the microrrede is working properly. Loads connected in this microgrid are powered according to operating profile predetermined in the project, with daily consumption of 962 Wh. This profile has been built according to a number of daily hours of operation of each residence load and can be modified by the user aiming energy savings. The interruption of non-priority loads can also be performed virtually. The system is monitored and managed through an Arduino controller, and remote access done through a computer connected to the data network (internet). Such remote access allows viewing the electrical and energetic behavior of the microrrede besides enabling the use of the system for technical experiments and implementing new distance control actions. The microgrid is installed on the C02 building at UNISINOS.

This masters thesis deals with the use of off-grid photovoltaic systems. First we explain the problems associated with the power and energy potential of photovoltaic system components, design of photovoltaic systems for autonomous operation and the financial evaluation. The result of the masters thesis is to create an application used to design the island system in the whole output range (the smallest power systems to house systems application). The conclusion of the masters thesis is devoted to designing three type of projects from our application – a garden cottage, a family cottage and the house.

The diploma thesis is focused on designer works of Savounius rotor for Raječko location. Finish of this design work is equipment, which will be used in this location as decentralized source of electrical energy. In thesis are written manufacturing processes as so as the process of design part including the calculation part, which is focused on characteristic quantity of Savonius rotor. Thesis is finished by econominal assessment of project.

This research argues that a diesel-based isolated electrical system can be optimized byintegrating a high share of solar photovoltaic (PV) generation and that the frequencystability of such system can be improved by including the PV participation in frequencyregulation. A case study is developed in order to explore an island’s expansion of theinstalled generating capacity and its optimization. This study uses the tool HOMER tosolve the optimization problem and PowerFactory to verify the frequency stability of theproposed system. The PV integration allows for a reduction of diesel fuel consumption,emissions and generation costs. Additionally, in high PV penetration scenarios, the reducedinertia in such systems can lead to high frequency deviations that may trip the systemprotection. The study demonstrates that the instantaneous frequency deviation after a loadand generation imbalance can be reduced by designing the PVs to operate with an allocatedreserve and a decentralized time-based secondary frequency control. The frequency stabilitywas achieved after different disturbance scenarios under high PV penetration and reducedavailable inertia, indicating that high PV integration is economically and technically feasiblein small island grids. / I detta examensarbete studeras hur ett dieselbaserat och isolerat elsystem kan optimeras genom att integrera en hög andel solceller (PV) i elproduktionen och att frekvensstabilitet kan förbättras när PV användas i regleringen. En fallstudie har utvecklats under denna forskning för att analysera en ökning av den installerade generationskapacitet vid en ö samt hur detta kan optimeras. I denna studie användas verktyget HOMER för modeloptimering och PowerFactory för att testa den optimerade systemfrekvens stabilitet. Med PV generation kan diesel konsumption, utsläpp och kostnader minskas för hela systemet. En hög andel PV i generationen reducerar elsystemet totala svängmassa vilket kan ledda till avvikelser i systemfrekvensen som kan ursaka att skyddsystem aktiveras. Studien demonstrerar att den momentana systemavvikelsen efter en obalans kan reduceras genom att designa PV i systemet med en allokerad reserv och en decentraliserad och tidsbaserad sekundär frekvensreglering. Frekvensstabiliteten nåddes i olika obalans scenarier med hög andel solcellgeneration och misnkat svängsmassa. Detta tyder på att en hög andel PV integration är både ekonomisk- och tekniskt möjligt i mindre elsystem.

This report is the result of a conducted Minor Field Study (MFS), to the greatestextent funded by the Swedish International Development Cooperation Agency(SIDA), in an attempt to design a system for evaluating smaller solar power systems indeveloping countries. The study was to the greater part conducted in Nairobi, Kenyain close collaboration with the University of Nairobi. The aim was to develop asystem that would use easily available components and keep the costs to a minimum,yet deliver adequate performance. The system would measure certain parameters of asolar power system and also relevant environmental data in order to evaluate theperformance of the system. Due to the specific competence of the collaboratinggroup at the University of Nairobi, a Kinetis Freescale K64-microcontroller with anARM-Cortex processor was selected as the core of the design. Components wereselected, schematics were drawn, a circuit board was designed and manufactured andsoftware was written. After 12 weeks a somewhat satisfying proof-of-concept wasreached at the end of the field study in Kenya. The project however proved howdifficult it is to go from first idea to a functional proof-of-concept during a limitedtimeframe, and also in an East-African country. The final proof-of-concept was testedat Mpala Research Centre in Kenya and despite containing some flaws proved that itwould indeed be possible to design a working system on the principles discussed inthis report. The system is open-source, so anyone may use and modify it.

The use of thermal storage energy, using phase change materials appears to be an effective way to store thermal energy storage with the benefits of the high amount of energy while maintaining isothermal nature of the process. PCM methods are used in latent thermal storage systems for heat pumps, as well as in solar engineering or for temperature control in spacecraft. The past decade has extended these principles for cooling and heating in the building. There are a number of PCM systems, which operate over a wide temperature range, are used in various applications. This document includes a brief overview of the development and analysis of available thermal storage working mainly on the principle of PCM.