Thesis (M. Sc.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Dec. 14, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Electrical and Computer Engineering, University of Alberta." Includes bibliographical references.

Thesis (MTech(Electrical engineering))--Cape Technikon, Cape Town, 2000 / The development of an automatic frequency control system for a miniature high frequency induction furnace is described. A background study into the fields of induction-heating, resonance, power electronic resonant converters and phase locked-loops are performed with relevance to this research. An analysis of the resonant load circuit is performed by means of a combination of measurement and numerical simulations. The study of the load behavior and power source is used as a :001 to aid effective implementation of the automatic frequency control system. This Jimulation data is used to detenninc the operating frequency range of the RLL system. A background study is performed in whieh several frequency-control schemes for power electronic converters are investigated. A brief summary, in which the basic requirements for a frequency control system with regards to this research are presented. Two revisions of the Automatic Frequency Control system (RLL) were implemented, on the induction furnace. Experimental results on both systems (Revl and Rev2), illustrating the necessity for frequency control are also presented. Future suggestions for optimizing the loop performance are presented. Further steps in the developmental process of the miniature high frequencj induction furnace are also discussed.

The ongoing change towards completely renewable power production in Sweden entails new challenges in maintaining a stable power system and puts greater demands on the frequency control. Hydropower caters for all frequency control in the Swedish grid today. However, the new challenges make it necessary to explore other technologies that potentially could provide frequency control. The aim of this master thesis is thus to map different technologies that potentially could deliver the reserves FCR and aFRR, with the main focus of investigating the economic potential of these technologies and their competitiveness during different seasons. The technologies investigated were lithium-ion batteries, flywheels, demand response and wind power plants. Different applications for these technologies were also investigated. The different investment alternatives were evaluated by calculating the net present value and the net present value ratio. The results show that the economic potential is greatest in cases where existing infrastructure could be used. Investments in stand-alone energy storage systems are not profitable today but might be so in the future as the prices continue to decrease. The results also show that many of the technologies and applications are competitive alternatives to hydropower during different seasons, which shows that there is potential in participating in the balancing markets with these technologies. However, it seems relevant to investigate further if, and if so how, the regulations on endurance can be adapted to actual conditions to further opening up the markets to more actors while maintaining a stable power system.

Synchronization is a very important part of every digital communication receiver. While in bandpass coherent transmission, frequency and phase synchronization play a very important role in reliable transmission, symbol timing recovery is a necessary part of every baseband and bandpass coherent receiver. This dissertation deals with the problem of synchronization in the presence of fading and interference. First, the performance of an automatic frequency control loop is investigated using two parameters of average switching rate and mean time to loss of lock. These parameters are derived in closed-form or as integral-form formulas for different scenarios of modulated and unmodulated signals in different fading channels when there is one interference signal present at the input of the AFC. Then, the results are generalized to the noisy fading scenario and it is shown that in Rayleigh fading case, the performance of AFC becomes better when the desired signal is noisier. In the second part, the problem of symbol timing recovery is investigated in systems that are subject to intersymbol interference and non-data-aided maximum likelihood synchronizer is derived in these channels. Then, a new simple bound on the performance of synchronizers is derived and compared to the previously known lower bounds. It is shown that while this lower bound solves the shortcomings of the well known modified Cramer-Rao bound at small values of signal-to-noise-ratio, it is much easier to compute compared to another well known bound, the detection theory bound. / Communications

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Increased use of variable energy and integration of electricity markets in the European Union have led to new challenges when balancing supply and demand in the grid. Load management is a possible way to manage these challenges by adjusting electricity consumption in order to balance the power system. Household appliances can be used for this purpose, for example by providing automatic frequency control. The aim of this master thesis is to investigate the potential of load management from private households and to examine how the power system is affected by a more flexible electricity consumption. The thesis focuses on fridges as automatic frequency control reserves and the ability of fridges to balance the power system. Attributes such as capacity, activation time, persistence and the effect of load reconnection has been modelled in Simulink, Matlab. Complementary interviews with actors from the electricity industry have been done to summarize their insights on demand response. The results indicate that fridges can be used as a part of the automatic frequency controlled reserve FCR-N, based on assumptions made in this study. However, current requirements imposed on balancing resources are not fully met by the fridges. In order for household appliances to provide the needed flexibility, some requirements might need to be rephrased. The results also show that the capacity for providing balancing services differs for positive and negative imbalances, as consumption can be reduced with 30 MW and increased with 66 MW. When controlling the fridges by moving the reference temperature, there is a risk that the appliances will synchronize with each other, i.e. reconnect or disconnect at the same time, resulting in frequency oscillations. It is therefore important that load management is designed to avoid this kind of behavior.

Increased use of variable energy and integration of electricity markets in the European Union have led to new challenges when balancing supply and demand in the grid. Load management is a possible way to manage these challenges by adjusting electricity consumption in order to balance the power system. Household appliances can be used for this purpose, for example by providing automatic frequency control. The aim of this master thesis is to investigate the potential of load management from private households and to examine how the power system is affected by a more flexible electricity consumption. The thesis focuses on fridges as automatic frequency control reserves and the ability of fridges to balance the power system. Attributes such as capacity, activation time, persistence and the effect of load reconnection has been modelled in Simulink, Matlab. Complementary interviews with actors from the electricity industry have been done to summarize their insights on demand response. The results indicate that fridges can be used as a part of the automatic frequency controlled reserve FCR-N, based on assumptions made in this study. However, current requirements imposed on balancing resources are not fully met by the fridges. In order for household appliances to provide the needed flexibility, some requirements might need to be rephrased. The results also show that the capacity for providing balancing services differs for positive and negative imbalances, as consumption can be reduced with 30 MW and increased with 66 MW. When controlling the fridges by moving the reference temperature, there is a risk that the appliances will synchronize with each other, i.e. reconnect or disconnect at the same time, resulting in frequency oscillations. It is therefore important that load management is designed to avoid this kind of behavior.