Abstract The goal of this research is to advance the state of the art in bulk power system reliability assessment. Bulk power system reliability assessment is an important procedure at both power system planning and operating stages to assure reliable and acceptable electricity service to customers. With the increase in the complexity of modern power systems and advances in the power industry toward restructuring, the system models and algorithms of traditional reliability assessment techniques are becoming obsolete as they suffer from nonrealistic system models and slow convergence (even non-convergence) when multi-level contingencies are considered and the system is overstressed. To allow more rigor in system modeling and higher computational efficiency in reliability evaluation procedures, this research proposes an analytically-based security-constrained adequacy evaluation (SCAE) methodology that performs bulk power system reliability assessment. The SCAE methodology adopts a single-phase quadratized power flow (SPQPF) model as a basis and encompasses three main steps: (1) critical contingency selection, (2) effects analysis, and (3) reliability index computations. In the critical contingency selection, an improved contingency selection method is developed using a wind-chime contingency enumeration scheme and a performance index approach based on the system state linearization technique, which can rank critical contingencies with high accuracy and efficiency. In the effects analysis for selected critical contingencies, a non-divergent optimal quadratized power flow (NDOQPF) algorithm is developed to (1) incorporate major system operating practices, security constraints, and remedial actions in a constrained optimization problem and (2) guarantee convergence and provide a solution under all conditions. This algorithm is also capable of efficiently solving the ISO/RTO operational mode in deregulated power systems. Based on the results of the effects analysis, reliability indices that provide a quantitative indication of the system reliability level are computed. In addition, this research extends the proposed SCAE framework to include the effects of protection system hidden failures on bulk power system reliability. The overall SCAE methodology is implemented and applied to IEEE reliability test systems, and evaluation results demonstrate the expected features of proposed advanced techniques. Finally, the contributions of this research are summarized and recommendations for future research are proposed.

Orientador: Walmir de Freitas Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-25T10:49:19Z (GMT). No. of bitstreams: 1 Meira_PauloCesarMagalhaes_D.pdf: 11828003 bytes, checksum: 693bdd2a6d139783c1aa0f2a05a3d6de (MD5) Previous issue date: 2014 / Resumo: A estratégia de eliminação de defeitos (faltas) empregada pela concessionária de distribuição de energia elétrica tem grande impacto na confiabilidade e na qualidade de energia do sistema. Por exemplo, a política de empregar religadores automáticos tipicamente tem um impacto benéfico nos índices de confiabilidade baseados na frequência e duração das interrupções sustentadas mas, por outro lado, tem um impacto negativo nos índices de qualidade de energia baseados na frequência de interrupções temporárias. Isto pode ser comprovado pelo número de concessionárias ao redor do mundo que estão revendo suas estratégias de empregar religadores automáticos de forma generalizada conforme cresce a preocupação do consumidor com a qualidade de energia. Somado a isso, tem-se o fato de o sistema estar sendo modernizado com o uso de mais equipamentos de monitoração e automação, como chaves seccionadoras automáticas, relés digitais, etc., dentro do contexto que se convencionou chamar redes inteligentes (smart grids). Portanto, atualmente, as estratégias de eliminação de faltas e de melhoria dos índices de confiabilidade e de qualidade de energia em sistemas de distribuição estão passando por modificações e têm atraído o interesse da comunidade científica e tecnológica. Este trabalho tem como objetivo desenvolver métodos para auxiliar na tomada de decisão sobre a estratégia de eliminação de defeitos em sistemas de distribuição via avaliação integrada dos índices de confiabilidade e qualidade de energia. Os métodos empregados são baseados no uso de registros históricos e de medições da concessionária, no cálculo de índices de confiabilidade e de qualidade de energia e em técnicas de otimização e de tratamentos estatísticos. Para permitir o emprego dos métodos a sistemas reais, algoritmos clássicos para análise de confiabilidade e qualidade de energia são revisitados e reformulados de forma a permitir sua aplicação a sistemas de grande porte em tempo de execução factível. São investigadas também formas de permitir a execução paralela e distribuída dos principais algoritmos empregados nos métodos propostos / Abstract: The fault elimination policy used by an electric energy distribution utility has great impact on the reliability and in the power quality of the system. For example, the policy of using automatic reclosers typically has a positive impact in the reliability indices based on frequency and duration of sustained interruptions but, on the other hand, has a negative impact on the power quality indices based on the frequency of temporary interruptions. This can be verified by the number of utilities around the world that are reevaluating their policies in using automatic reclosers in a generalized fashion as the customers demand better power quality. At the same time, the systems are being modernized, including the usage of more monitoring and automation equipment, such as automatic sectionalizing switches, digital relays, etc., in a context that is usually called smart grids. Therefore, currently, the policies regarding fault elimination and improvement of the reliability and power quality indices in distribution system are being reformulated and have attracted the interest of the academic and technology communities. The objective of this thesis is to develop methods to assist in the decision-making process on the fault elimination policies in distribution systems using the integrated evaluation of reliability and power quality indices. The methods are based on the use of historical records and utility measurements, in the computation of reliability and power quality indices, in optimization techniques and statistical analysis. To achieve the implementation of the methods in actual systems, the classic algorithms used to analyze the reliability and power quality are revisited and reformulated in order to allow their application to large-scale systems in feasible running time. Alternatives to allow the parallel and distributed execution of the main algorithms of the proposed methods are also explored / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

Indiana University-Purdue University Indianapolis (IUPUI) / Reliability of the wide-area power system is becoming a greater concern as the power grid is growing. Delivering electric power from the most economical source through fewest and shortest transmission lines to customers frequently increases the stress on the system and prevents it from maintaining its stability. Events like loss of transmission equipment and phase to ground faults can force the system to cross its stability limits by causing the generators to lose their synchronism. Therefore, a helpful solution is detection of these dynamic events and prediction of instability. Decision Trees (DTs) were used as a pattern recognition tool in this thesis. Based on training data, DT generated rules for detecting event, predicting loss of synchronism, and selecting stabilizing control. To evaluate the accuracy of these rules, they were applied to testing data sets. To train DTs of this thesis, direct system measurements like generator rotor angles and bus voltage angles as well as calculated indices such as the rate of change of bus angles, the Integral Square Bus Angle (ISBA) and the gradient of ISBA were used. The initial method of this thesis included a response based DT only for instability prediction. In this method, time and location of the events were unknown and the one shot control was applied when the instability was predicted. The control applied was in the form of fast power changes on four different buses. Further, an event detection DT was combined with the instability prediction such that the data samples of each case was checked with event detection DT rules. In cases that an event was detected, control was applied upon prediction of instability. Later in the research, it was investigated that different control cases could behave differently in terms of the number of cases they stabilize. Therefore, a third DT was trained to select between two different control cases to improve the effectiveness of the methodology. It was learned through internship at Midwest Independent Transmission Operators (MISO) that post-event steady-state analysis is necessary for better understanding the effect of the faults on the power system. Hence, this study was included in this research.