This thesis aims to simulate and find out more about the electrical dynamics of asix-phase exciter for hydropower generators. Because ordinary electric circuit-basedsimulation software only simulate three-phase electrical systems, a FEM-basedsoftware is used for the electrical dynamics simulations of the six-phase system. Theobjective is to analyse the pulsation behaviour of the rectified electrical output on thesix-phase system and compare it to the three-phase system. The three-phase systemis also simulated with filters with the aim of decreasing the amplitude of the pulsationson the electrical output.It is expected that an upgraded system from a three-phase system to a six-phasesystem should double the pulsation frequency on the rectified electrical output.However, the result shows that the rectified electrical output of the six-phase systemconsists of pulsations with unexpected frequencies. The simulated RL-filter on thethree-phase system shows only insignificantly small changes on the rectified electricalpulsation amplitude.

The first topic of this thesis is a novel voltage tripler using 4 clocks with different phases. Both the positive and negative polarities of the voltage are generated to serve as the boosted voltage and the back bias voltage. The proposed design is carried out by pass transistors and switched capacitors. The second topic is a low-power discrete cosine transform (DCT) processor. It is suitable for portable applications. The number of clock cycles needed for processing an 8¡Ñ8 block of pixels is increased, but the chip area is reduced. The reduction of the chip area leads to the reduction of the power dissipation.

The subject of this Master Thesis is construction of hydrogen generator for automotive industry. The objective is to design system which is able to produce required amount of gas. The master thesis includes basic analysis of situation, mathematical equations of electrolytic process and procedure of mechanical design according required power of generator. The next part is design of power control system of hydrogen generator based on informations from automobile. The last part describes power supply of whole system with electric energy. The output of the Master Thesis is the whole design of hydrogen generator including sensor system and control system. The thesis also includes suggestions for next improvements and research.

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Random numbers are important for gaming, simulation and cryptography. Random numbers have been generated using analog circuitry. Two problems exist with using analog circuits in a digital design: (1) analog components require an analog circuit designer to insure proper structure and functionality and (2) analog components are not easily transmigrated into a different fabrication technology. This paper proposes a class of random number generators that are constructed using only digital components and typical digital design methodology. The proposed classification is called divergent path since the path of generated numbers through the range of possible values diverges at every sampling. One integrated circuit was fabricated and several models were synthesized into a FPGA. Test results are given.

Den här rapporten innehåller en selektivplan som upprättats i samband med utbyte av tre generatorer på Arctic Paper i Munkedal, samt flera selektivplansuppdateringar i övriga skydd. Arbetet har som syfte att bygga upp fördjupande kunskap i säkringsfri teknik i industriella elanläggningar, vilket genomförs som ett examenarbete för högskoleutbildning som elkraftsingenjör. På pappersbruket finns idag tre gamla vattenkraftsgeneratorer. Två av de tre nuvarande generatorerna är små och mycket gamla, generatorer som ska bytas ut mot två nya 3MVA synkrongeneratorer. En av de gamla generatorerna ska användas även i framtiden som reserv. Målet med ombyggnadsprojektet är att öka effekten med upp till tre gånger samt att fördubbla energi produktionen. Ställverk till generatorerna har specificerats tidigare i ombyggnadsprojektet. Selektivplanen inkluderar inställningar av reläskydd och effektbrytare för generatorerna. Dessutom kommer befintliga överströmsskydd i anläggningen beaktas. Rapporten baseras på selektivitetsteori och beräkningar av kortslutningsströmmar. Rapporten innefattar även uppdatering av vissa selektivplaner i den befintliga elanläggningen i pappersbruket, detta genom att diskutera problemet och justera inställningar av de befintliga reläskydden Tekniska beräkningar och reläinställningsplaner ska fungera som verifikation och dokumentation.

The Hayes Coastal Engineering Laboratory is a new laboratory with two water basins: a 45.72-meters long, 3.66 meters wide and 3.06 meters deep Tow Tank with sediment pit for dredging and current flow studies, and a 36.58 meters long, 22.86 meters wide and 1.22 meters deep 3D Wave Basin for coastal wave studies. In order to assess the capabilities of the lab a series of tests were done in both tanks. Hydrodynamic tests in the Tow Tank using a Micro Acoustic Doppler Velociometer measured current flow in the tank and assessed the efficacy of different filters to stabilize flow patterns. A concrete dam structure installed near the reversed diffusers most effectively stabilized flow of all the configurations tested. Wave tests were conducted in the 3D Wave Basin with the newly-installed 48 paddle Rexroth wave generator at 0.5 and 1.0 meter water depths using wired and wireless capacitance wave gauges. These tests measured characteristics of the generated waves and reflection from the rubble-mound beach. In addition, initial testing of the Active Reflection Absorber (ARA) system was done. Correlating the wave data to the theoretical wave being produced showed that with water depth of 0.5 meters the 0.1 meter waves were well-formed, but the 0.2 meter waves showed energy loss and lower correlation. The results from one meter water depth wave tests showed good formation of 0.2 meter waves. In nearly all wave tests with pool buoys installed the waves were better formed with good correlation and a better fitting power spectrum. The beach reflection was within the expected value range, being ten percent and below for most tests. ARA, while operational, needs to be further tuned to find the settings that will increase its effectiveness.

Ett kärnkraftverk producerar inte bara elenergi, det är även beroende av det bl.a för kylning av reaktorn. Därför finns åtskilliga säkerhetssystem för reservkraft och ett av dessa system är dieseldrivna generatorer. På en av reaktorerna i Oskarshamn har man fyra sådana generatorer men de börjar bli gamla och det finns ett behov av att skaffa en ny generator för att kunna frigöra de gamla en i taget och göra en grundlig genomgång på dem. Det här examensarbetet kom till för att undersöka om det är möjligt att få fram en ny generator som går att använda som ersättare medans en gammal plockas ner för total genomgång. Det omfattar även kringutrustningen till generatorerna som är lika viktig för dess funktion. För att få fram vad som krävs har jag behövt sätta mig in i hur systemet är uppbyggt och fungerar. Sedan har jag använt mina egna och min handledare på OKG:s kunskaper för att ta fram en specifikation på vad som krävs av en ny generator. Sedan har mycket tid lagts på att leta uppgifter och värden i datablad för att kunna slutföra specifikationen som också är resultatet av arbetet. Jag har även varit i kontakt med en generatortillverkare för att få veta hur dem ställer till kraven och utifrån det kommit med förslag på hur man ska gå vidare med det här projektet. Det har även genomförts en mätning på de befintliga generatorerna för att undersöka skicket på dem.

Stochastic Weather Generators (SWG) try to reproduce the stochastic patterns of climatological variables characterized by high dimensionality, non-normal probability density functions and non-linear dependence relationships. However, conventional SWGs usually typify weather variables with unjustified probability distributions assuming linear dependence between variables. This research proposes an alternative SWG that introduces the advantages of the Copula modeling into the reproduction of stochastic weather patterns. The Copula based SWG introduces more flexibility allowing researcher to model non-linear dependence structures independently of the marginals involved, also it is able to model tail dependence, which results in a more accurate reproduction of extreme weather events. Statistical tests on weather series simulated by the Copula based SWG show its capacity to replicate the statistical properties of the observed weather variables, along with a good performance in the reproduction of the extreme weather events. In terms of its use in crop growth models for the ratemaking process of new insurance schemes with no available historical yield data, the Copula based SWG allows one to more accurately evaluate the risk. The use of the Copula based SWG for the simulation of yields results in higher crop insurance premiums from more frequent extreme weather events, while the use of the conventional SWG for the yield estimation could lead to an underestimation of risks.

This thesis has been performed in the university context for Master thesis 30 credits,which is a compulsory exercise in order to gain a degree in electrical engineering. The thesis main objectives were to investigate how the damping and the stiffness of ahydroelectric generator changed depending on different parameter values, and to testa new mathematical model to calculate the damping and stiffness constants Kd and Ks.The work has been performed at the request of VG Power, but has been performedat the division for electricity at Uppsala University. The reason for undertaking thisthesis was to ensure that generators are robust. But also when building future modelsfor generators, to have a system that can be used to compute robustness. During this thesis a power cabinet has also been constructed to be able to test thesimulated model on a real generator. Under the first five weeks a power cabinet wasconstructed in the laboratory at the division for electricity. The tests were thenperformed at a generator with a rated power of 75 kVA.