It is the purpose of this study to show how successfully electric power systems were operated by smaller units of government. One of the most notable power plants is operated in Denton, Texas. In this study, the history of this system will be presented, followed by an analysis of its social and economic significance.

[pt] Com o uso da teoria das probabilidades consegue-se um método para medida da confiabilidade dos sistemas de potência, bastante preciso. O presente trabalho consubstancia a teoria que envolve o cálculo da confiabilidade de um sistema de geração, o planejamento desse sistema, a programação da manutenção das unidades geradoras - de modo a manter um nível de confiabilidade constante durante um ano - e um programa de computador como ilustração dos métodos apresentados. / [en] The use of probability theory is a tool for a accurate reliability evaluation of power systems. This paper explains the theory envolving, reliability analysis of a generating system, planning of those systems, maintenance scheduling of generating units to maintain a constant reliability level during the year and a computer program to ilustrate all the introduced methods.

The aim of generator maintenance scheduling (GMS) in an electric power system is to allocate a proper maintenance timetable for generators while maintaining a high system reliability, reducing total production cost, extending generator life time etc. In order to solve this complex problem a genetic algorithm technique is proposed here. The paper discusses the implementation of GAs to GMS problems with two approaches: generational and steady state. The results of applying these GAs to a test GMS problem based on a practical power system scenario are presented and analysed. The effect of different GA parameters is also studied

Reliable, affordable access to electrical power is a requirement for almost all aspects of developed societies. Challenges associated with reducing carbon emissions has led to growing interest in nuclear-renewable hybrid energy systems (N-RHES). Much work has already been done in suggesting and analyzing various N-RHES using a variety of optimization techniques and assumptions. This work builds upon previous techniques for simultaneous combined design and dispatch optimization (CDDO) for hybrid energy systems (HES). The first contribution of this work is the development and application of sensitivity analysis tailored to the combined design and dispatch optimization problem. This sensitivity analysis cover uncertainty in design parameters, time series and dispatch horizon lengths. The result is a deeper insight into which sources of uncertainty are most important to account for and how the uncertainty around these sources can be quantified. The second contribution of this work is a novel multi-scale optimization algorithm for the combined HES design and dispatch optimization. This algorithm supports optimization of nonlinear models over very long-time horizons. This method is based on a multi-dimensional distribution of the optimal capacities for a system as determined by a large number of combined design and dispatch optimization problems each covering a subset of the complete time horizon. This method shows good agreement with the direct solution to multiple example systems and is then used to solve a problem with a dispatch horizon length 112.5 times longer than is solvable directly. The third contribution of this work is the application of the novel multi-scale method to three HES. Each of the application systems is used to demonstrate the strengths, validation and applicability of the developed algorithm to a wide range of possible HES/NHES designs.

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[pt] Uma das fases importantes no planejamento dos Sistemas Elétricos de Potência é a verificação do seu comportamento dinâmico. Sob este aspecto é conveniente que se tenha uma modelagem mais real possível de todos os componentes do sistema, havendo particular interesse numa boa representação principalmente das máquinas (geradores e síncronos). Ultimamente, os Compensadores Estáticos (SVS) tem sido um elemento valioso no controle da potência reativa dos sistemas Elétricos de EAT. Desta forma, os programas digitais até então utilizados tiveram que ser convenientemente modificados a fim de considerar este novo equipamento. A finalidade deste trabalho é apresentar a representação dos SVS nos programas de estabilidade. O enfoque principal será dados aos SVS controlados a tiristores (TCR, TCT, TSC ou mistos) nos quais há intervenção de sistemas específicos de controle. Com base na modelagem proposta, é feita uma análise da operação dos SVS a tiristores em regime permanente e, em transitório. Conjuntamente com a apresentação dos vários tipos de SVS a tiristores, é introduzida uma metodologia para a determinação de seus valores nominais, suas principais características operativas, fazendo-se, sempre que possível, uma comparação com outros tipos de Compensadores Estáticos e, com os Compensadores Síncronos atualmente em operação. / [en] One of the most important phases of power systems planning, is the examination of its dynamic behavior. It is convenient under this aspect, to have the models of all components pertaining the system, as close as possible to the real conditions of operation being of particular interest a good representation, mainly of the machines (generators and synchronous compensators). Lately, the static compensators (SVS), have been an important component in the control of reactive power for the UHV electrical systems. Due to this fact, the digital programs used until then, had to be conveniently modified so as to consider this new equipment. The purpose of the present work, is to introduce the representation of the SVS in the stability programs. Special care will be give to the SVS controlled by thyristors (TCR, TCT, TSC or mixed), in which the intervention of specific control systems takes place. Based upon the proposed models, an analysis of the operation of the thyristors SVS in permanent and transient regimes is performed. Together with the presentation of various types of thyristors SVS, it is introduced methods to determine nominal values, main operational characteristics, always comparing, when possible, to other types of static compensators, as well as, with the synchronous compensators in operation.

This thesis reports on a novel approach to cable thermal field and ampacity computations using a newly proposed concept of perturbed finite-element analysis, which involves the use of derived sensitivity coefficients associated with various cable parameters of interest. It uses the sensitivity coefficients to achieve optimal cable performance. The proposed model provides a quick methodology, based on the finite element model, to assess the cable thermal performance subject to variations in the cable thermal circuit parameters. Furthermore, an optimization model for an underground power cable thermal circuit, based on generated gradients was developed, where subsequent utilization of the derived sensitivities as gradients of objective functions in a general framework of power cable performance optimization is presented. This comprehensive model uses the more accurate perturbed finite element method, which enables calculation of the objective function value and its gradients, without sacrificing the model accuracy. The algorithm developed was applied to various benchmark cable systems with their actual configurations, for different practical cable performance optimization objectives of interest to power utilities operators. The thermal field of an underground power cable sample directly buried in the soil was observed in the laboratory using a developed full size experimental setup. The investigation involves all parts of the thermal circuit parameters including cables composition, surrounding soil and boundaries phenomena. This experimental set was used to validate the developed simulation model by comparing the simulation results with the real laboratory measurements. Such experimental verification confirmed the accuracy of the newly introduced finite element sensitivity methodology. / This thesis reports on a novel approach to cable thermal field and ampacity computations using a newly proposed concept of perturbed finite-element analysis, which involves the use of derived sensitivity coefficients associated with various cable parameters of interest. It uses the sensitivity coefficients to achieve optimal cable performance. The proposed model provides a quick methodology, based on the finite element model, to assess the cable thermal performance subject to variations in the cable thermal circuit parameters. Furthermore, an optimization model for an underground power cable thermal circuit, based on generated gradients was developed, where subsequent utilization of the derived sensitivities as gradients of objective functions in a general framework of power cable performance optimization is presented. This comprehensive model uses the more accurate perturbed finite element method, which enables calculation of the objective function value and its gradients, without sacrificing the model accuracy. The algorithm developed was applied to various benchmark cable systems with their actual configurations, for different practical cable performance optimization objectives of interest to power utilities operators. The thermal field of an underground power cable sample directly buried in the soil was observed in the laboratory using a developed full size experimental setup. The investigation involves all parts of the thermal circuit parameters including cables composition, surrounding soil and boundaries phenomena. This experimental set was used to validate the developed simulation model by comparing the simulation results with the real laboratory measurements. Such experimental verification confirmed the accuracy of the newly introduced finite element sensitivity methodology. / Thesis / Doctor of Engineering (DEng)

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The power system has long been operated in a shroud of introspection. Only recently have dynamic, wide-area time synchronized grid measurements brought to light the complex relationships between large machines thousands of miles apart. These measurements are invaluable to understanding the health of the system in real time, for disturbances to the balance between generation and load are manifest in the propagation of electromechanical waves throughout the grid. The global perspective of wide-area measurements provides a platform from which the destructive effects of these disturbances can be avoided. Virginia Tech's distributed network of low voltage frequency monitors, FNET, is able to track these waves as they travel throughout the North American interconnected grids. In contrast to other wide-area measurement systems, the ability to easily measure frequency throughout the grid provides a way to identify, locate, and analyze disturbances with high dynamic accuracy. The unique statistical properties of wide-area measurements require robust tools in order to accurately understand the nature of these events. Expert systems and data conditioning can then be used to quantify the magnitude and location of these disturbances without requiring any knowledge of the system state or topology. Adaptive application of these robust methods form the basis for real-time situational awareness and control. While automated control of the power system rarely utilize wide-area measurements, global insight into grid behavior can only improve disturbance rejection. / Ph. D.