This work demonstrates the theoretical and experimental feasibility of a induction generator to work as an attenuator of the harmonics in main generators of on the electric power system, i.e., the synchronous generators. The induction and synchronous machines were analyzed in physical terms and established mathematical modeling in the frequency domain in order to prove the purpose of the thesis. Computer simulations were also carried out in the time domain and laboratory tests were made to check levels of attenuation of current harmonics (THDi) in accordance with the maximum standardized voltage harmonic distortion (THDv). Furthermore, this work presents a study of technical and economical feasibility of a typical application. / Este trabalho demonstra a viabilidade teórica e experimental de um gerador de indução funcionar como um atenuador dos harmônicos nos geradores principais do sistema elétrico de potência, ou seja, os geradores síncronos. Foram analisadas as máquinas de indução e síncronas do ponto de vista físico e estabelecidas modelagens matemáticas no domínio da frequência, a fim de comprovar o objetivo da tese. Foram realizadas também´em, simulações computacionais no domínio do tempo e ensaios em laboratório para verificar os n´níveis de atenuação de harmônicos de corrente (THDi) em conformidade com os limites máximos de distorções harmônicas de tensão (THDv) normalizados. Apresenta-se também neste trabalho um estudo de viabilidade técnica e econômica de uma aplicação típica. / Doutor em Ciências

The aim of the project is to design a concept of function generator with digital synthesis. The device will be controlled using microprocessor which allows synthesizing basic functions (sin, square, raw) as well as arbitrary functions stored in memory. User friendly graphical interface will be controlled by keyboard and rotary switch (IRC). The work emphasizes correct selection of DDS clock source, circuit elements and proper application of signal filtration method with attention to low distortion and low output phase noise.

The thesis deals with issues of random numbers, their generating and use in cryptography. Introduction of work is aimed to resolution of random number generators and pseudo--random number generators. There is also included often used dividing generators on software and hardware. We mention advantages and disadvantages of each type and area of their use. Then we describe examples of random and pseudorandom numbers, mainly hardware based on physical phenomenon such as the decay of radioactive material or use atmospheric noise. The following part is devoted to suggestion own random number generator and a description of its functionality. In the second half of the work we devote to the field of cryptography. We know basic types of cryptographic systems, namely symmetric and asymmetric cryptosystems. We introduce a typical representant the various type and their properties. At the end of the work we again return to our random number generator and verify the randomness generated numbers and obtained cryptograms.

Parametry nahradniho obvodu synchronniho stroje znance ovlivnuji jeho chovani jak pri statickem provozu, tak predevsim pri nahlych dynamickych jevech a poruchovych stavech. Prace je zamerena na zhodnoceni dostupnych metod pro vypocet techto parametru pomoci Metody konecnych prvku. Prvni cast je venovana teoretickemu popisu zakladnich principu Metody Konecnych Prvku a jejich aplikaci na reseni problemu elektromagnetickeho pole v elektrickych strojich. Zaroven take shrnuje zakladni usporadani nahradniho obvodu synchroniho stroje, principi jeho konstrukce a zakladni funkci. Druha cast je venovana praktickemu vypoctu reaktanci nahradniho obvodu synchronniho stroje. S pomoci MKP jsou vypocteny synchronni reactance s uvazovanim vzajmeneho magnetickeho pusobeni proudu v d a q ose. Pro vypocet transientnich a subtransientnich reaktanci jsou navrzeny ctyri odlisne metody a jsou zhodnoceny z hlediska pozadovane presnosti vypoctu a narocnosti na vypocetni cas. Zaverecna cast popisuje zakladni merici metody pro urceni parametru nahrandniho obvodu na skutecnem stroji. Kapitola take obsahuje srovnani simulace trifazoveho zkratu synchronniho stroje s realnou zkouskou provedenou laboratorne. Zaver obsahuje srovnani jednotlivych metod a navrh optimalniho postupu pro vypocet zkoumanych parametru.

The target of this diploma thesis is design of cogeneration unit with following requirements: • Installation of new unit instead of the old and used up one. • Electric energy supply within Supportive service – fast starts • Greening (replacement of coal with natural gas) At the beginning I deal with the current state of old unit. In the next part there is the design of new technological unit, which consists of design of boilers, gas engines, steam turbines. Final phase of the thesis includes economical analysis focused on setting of financial return.

This work was carried out on behalf of Science Safari. Science Safari wants to create a product that facilitates the understanding of how much physical work is required to create electrical energy. This is done by cranking the pedals of a bicycle. The purpose of this work is to create a control unit that keeps the torque required to crank the pedals close to constant. The torque can be kept constant by creating a variable load for the generator, in this case, a pulse modulated JFET is used. The output of the current sensor and the Hall-effect sensor are used to calculate the required resistance of the JFET to keep constant torque. All this is controlled via a Raspberry Pi 3 Model B (RPi) which also shows real-time values on a display. The functionality of the sensors and JFET has largely been completed, but the assembly of all components is lacking in this work. / Detta arbete är utfört i uppdrag av Science Safari. Science Safari vill skapa en produkt som underlättar förståelsen av hur mycket fysiskt arbete som krävs för att skapa elektrisk energi. Detta genom att användaren vevar på en cykels pedaler för hand. Syftet med detta arbete är att skapa en styrenhet som ungefär håller ett konstantvridmomentet på en cykels pedaler. Vridmomentet kan hållas konstant genom att skapa en variabel last till generatorn, med hjälp av en pulsmodulerad JFET. För att beräkna vilken resistans JFETen ska ha för att hålla konstant vridmoment används en strömsensor och en Hall-effect sensor. Allt detta styrs via en Raspberry Pi 3 ModelB som även visar värden i realtid på en display. Funktionaliteten av sensorerna och JFET har till stor del färdigställts men sammansättning av alla komponenter saknas i detta arbete.

As new requirements for grid connected generators were implemented, the requirements for evaluating the Fault Ride Through capabilities of the generators became stricter. When refurbishing a power unit, proof that the power unit meet the requirements must be submitted to the authorities. Performing simulations of the Fault Ride Through of a production unit is an extensive process and requires advanced simulation models and tools. Therefore, the need for a simplified tool for estimating the Fault Ride Through capability arose, which is what the project produced. Also, knowledge of which production module characteristics (such as the generator parameters, transformer and excitation system) have the largest effect on the Fault Ride Through time, would also be beneficial. Through the creation of Simulink simulation models of two hydropower stations and a sensitivity analysis of station parameters, the relative effect of the parameters on the Fault Ride Through time is estimated and implemented into a time independent Fault Ride Through time estimation tool, based on the Equal Area criterion. The purpose of the time-independent Fault Ride Through time estimation tool is to provide an insight into the approximate transient stability of the hydropower station and which parameters affect the performance the most. Simulations show that the transient reactance of the generator, the generator inertia, the transient time constant and the transformer inductance have the largest effect on the Fault Ride Through capability. The results show that a simplified tool cannot estimate the Fault Ride Through as accurately as a time-domain simulation model can.

This thesis is a study on an unconventional slow speed direct drive permanent magnet (PM) generator. Unlike a standard permanent magnet synchronous generator (PMSG) which has the copper coils wound around iron teeth, the work in this thesis will present a generator where the copper coils are directly mounted on the stator which eliminates the slots and teeth in the generator. By having a slotless design it is possible to eliminate cogging torque, iron losses in teeth and achieve a lightweight design. These characteristics can prove useful when developing generators for an application such as wind turbines, or more specifically vertical axis wind turbines (VAWTs) in remote areas where weight and serviceability is of concern. This thesis consists of two main parts where the main focus was on the design and simulation of slotless generators. The second part of the thesis was to investigate an available slotless axial flux machine. For the simulations, three different models were created in 2D using CAD software. Two of the models were double-rotor slotless generators and one was a single rotor variant. The electromagnetic properties of these models were analysed using FEMM and COMSOL. The results showed that the double rotor variant with the smaller magnets were more favourable considering the price of magnets and no iron core losses. The experimental results of the axial flux machine gave insight into the construction of commercially available axial slotless generators which could be used to further analyse these types of machines.

Aufgrund von steigenden Energiekosten und einer sukzessive steigenden öffentlichen sowie politischen Forderung nach Umweltbewusstsein und Nachhaltigkeit, ist die Effizienzsteigerung von Gesamtsystemen einer der treibenden Kräfte für innovative, technologische Neuheiten geworden. Besonders bei der Entwicklung von verbrennungsmotorisch angetriebenen Fahrzeugen wurden z.B. durch die Hybridisierung von Antriebssträngen, die die Rekuperation von kinetischer Energie ermöglichen, Technologien zur Energieeinsparung etabliert. Da bei Verbrennungsmotoren ein hoher Anteil der im Kraftstoff gespeicherten Energie technologiebedingt als Abwärme im Abgas verloren geht, bietet die Wärmerekuperation ein weiteres hohes Potential für weitere Einsparungen. Diese ist z.B. mit Hilfe von thermoelektrischen Generatoren (TEG) möglich, die einen Wärmestrom direkt in elektrische Energie umwandeln. Zur effizienten TEG-Systemgestaltung ist ein hoher Temperaturgradient über dem thermoelektrisch aktivem Material notwendig, der wiederum zu kritischen thermomechanischen Spannungen im Bauteil führen kann. Diese werden zum einen durch die unterschiedlichen Temperaturausdehnungskoeffizienten der verschiedenen Materialien und zum anderen durch die mechanische Anbindung auf der heißen und kalten Seite des TEG verursacht. Somit liegt ein Zielkonflikt zwischen dem thermoelektrischen Systemwirkungsgrad und der mechanischen Festigkeit des Bauteils vor. In dieser Arbeit wird mit Hilfe einer mehrkriteriellen Parameteroptimierung eines vollparametrisierten FE-Modells des TEG in ANSYS WORKBENCH eine Methode vorgestellt, den thermoelektrischen Wirkungsgrad bei gleichzeitiger Reduktion der thermomechanischen Spannungen zu optimieren. Zur Optimierung kommt dabei ein genetischer Algorithmus der MATLAB GLOBAL OPTIMIZATION TOOLBOX zum Einsatz. Der Modellaufbau wird in ANSYS WORKBENCH mit der Makro-Programmiersprache JSCRIPT realisiert. Als Ziel- und Bewertungsfunktionen wird die mechanische Belastung jedes Bauteils im TEG ausgewertet und dessen elektrische Leistungsdichte berechnet. Die Ergebnisse zeigen, dass mit Hilfe der vorgestellten Methodik eine paretooptimale Lösung gefunden werden kann, die den gestellten Anforderungen entspricht.

Floating offshore wind turbines show great potential within the energy industry, especially for deeper waters where traditional fixed-bottom turbines cannot be used. Offshore locations also offer stronger and more stable winds compared to onshore locations. The study explores the impact of the secondary machine efficiency on the electricity production in a Counter Rotating Axis Floating Tilting (CRAFT) wind turbine. The counter-rotating design holds promise for achieving high overall system efficiency.  MATLAB simulations show that it is possible to maintain a lower secondary machine efficiency without compromising stability. Reviewing two control systems confirms that using a robust control algorithm with optimized TSR ensures system stability in both high and low winds. A decrease in secondary electric machine efficiency from 97% to 93% resulted in a 0.03% reduction in annually generated electricity, whereas a similar decrease in primary electric generator efficiency led to a 1% reduction instead. Decreasing the secondary machine efficiency further to 83% resulted in a 0.1% reduction in annual generated electricity. Thus, the secondary machine's efficiency is shown to be less critical for the electricity production than the primary generator’s efficiency.  Choosing an asynchronous over a synchronous option as the secondary machine is economically advantageous since its lower efficiency of 83% instead of 97% does not significantly affect the electricity production. Moreover, the lower magnet cost for the asynchronous machines positively impacts economic metrics like LCoE, NPVI and payback period, making the asynchronous generator a more favourable economic choice. Further research areas to obtain higher accuracy include integrating differences in maintenance costs and conducting a more in-depth assessment of the investment costs associated with the two types of generators. Additionally, considering airflow losses around turbine blades and airflow interaction amongst the turbines could further enhance the model accuracy.