The purpose of this research is to develop a method of making system equivalents for the Real Time Digital Simulator (RTDS), which should enhance its capability of simulating large power systems. The proposed equivalent combines a Frequency Dependent Network Equivalent (FDNE) for the high frequency electromagnetic transients and a Transient Stability Analysis (TSA) type simulation block for the electromechanical transients. The frequency dependent characteristic for FDNE is obtained by curve-fitting frequency domain admittance characteristics using the Vector Fitting method. An approach for approximating the frequency dependent characteristic of large power networks from readily available typical power-flow data is also introduced. A new scheme of incorporating TSA solution in RTDS is proposed. This report shows how the TSA algorithm can be adapted to a real time platform. The validity of this method is confirmed with examples, including the study of a multi in-feed HVDC system based network.

The purpose of this research is to develop a method of making system equivalents for the Real Time Digital Simulator (RTDS), which should enhance its capability of simulating large power systems. The proposed equivalent combines a Frequency Dependent Network Equivalent (FDNE) for the high frequency electromagnetic transients and a Transient Stability Analysis (TSA) type simulation block for the electromechanical transients. The frequency dependent characteristic for FDNE is obtained by curve-fitting frequency domain admittance characteristics using the Vector Fitting method. An approach for approximating the frequency dependent characteristic of large power networks from readily available typical power-flow data is also introduced. A new scheme of incorporating TSA solution in RTDS is proposed. This report shows how the TSA algorithm can be adapted to a real time platform. The validity of this method is confirmed with examples, including the study of a multi in-feed HVDC system based network.

Orientador: Laurence Duarte Colvara / Banca: Carlos Roberto Minussi / Banca: Wagner Peron Ferreira / Resumo: Este trabalho apresenta um estudo sobre a relação entre os principais tipos de bifurcações que ocorrem em sistemas elétricos de potência e em quais ocasiões elas podem ocorrer em máquinas síncronas com ou sem RAT (Regulador Automático de Tensão). Para explorar tais fenômenos, primeiramente o sistema é modelado, sendo utilizado para o caso MBI (Máquina - Barramento In nito) o modelo um eixo e, então, a matriz de estado é calculada para a análise dos autovalores. Para os sistemas multimáquinas estudados, são incluídos dois enrolamentos amortecedores nos eixos d ¡ q. São então apresentados os métodos de análise de estabilidade transitória convencionais, amplamente utilizados, conhecidos como método Tradicional e Método Direto. As condições para a ocorrência de bifurcações são analisadas utilizando os coe - cientes linearizados do modelo de He ron-Phillips para o caso MBI, onde é mostrado que se espera perder a estabilidade para o sistema com regulador automático de tensão através de uma bifurcação de Hopf e para o caso sem RAT através de uma bifurcação Sela-Nó. Por m, é analisado o ciclo-limite para o caso de uma máquina - barramento in nito e para sistemas multimáquinas através do modelo não-linear. A região de estabilidade é analisada no plano de fase, sendo mostrada a necessidade de incluir a variação de uxo no enrolamento de campo para uma análise correta da estabilidade. É também mostrado que este ciclo-limite pode reduzir a fronteira de estabilidade calculada pelo método convencional. / Abstract: The aim of this study is the relation among main types of bifurcations that occur in electrical power systems and the circumstances they can happen with the synchronous machines considered with or without AVR (Automatic Voltage Regulator). To explore such phenomena, the system is rst modeled with the synchronous machines described by the one axis model for the MIB (Machine - In nite Bus) case , and so the state matrix is computed for the analysis of its eigenvalues. For multimachine systems case two windings dampers are included in d-q axes. The conditions for the occurrence of bifurcations are analyzed using the coe cients of the He ron-Phillips model for MIB case, where it is shown that one expects the system with automatic voltage regulator lose synchronism through a Hopf bifurcation and for the case without RAT through a Saddle- Node Bifurcation. Finally, the nonlinear model is accounted for in order to consider the limit-cycle for the case of one machine - in nite bus case as well as for multimachine system. Since internal voltage a ects the boundary of the stability region it must be considered. Then the phase portrait does not su ce and the trajectories must to be observed in a sub space de ned with the internal voltage. It is also shown that this limit-cycle can reduce the boundary of stability calculated by means of the direct method. / Mestre

abstract: Electric power system security assessment is one of the most important requirements for operational and resource planning of the bulk power system ensuring safe operation of the power system for all credible contingencies. This deterministic approach usually provides a conservative criterion and can result in expensive bulk system expansion plans or conservative operating limits. Furthermore, with increased penetration of converter-based renewable generation in the electric grid, the dynamics of the grid are changing. In addition, the variability and intermittency associated with the renewable energy sources introduce uncertainty in the electricity grid. Since security margins have direct economic impact on the utilities; more clarity is required regarding the basis on which security decisions are made. The main objective of this work is to provide an approach for risk-based security assessment (RBSA) to define dynamic reliability standards in future electricity grids. RBSA provides a measure of the security of the power system that combines both the likelihood and the consequence of an event. A novel approach to estimate the impact of transient stability is presented by modeling several important protection systems within the transient stability analysis. A robust operational metric to quantify the impact of transient instability event is proposed that incorporates the effort required to stabilize any transiently unstable event. The effect of converter-interfaced renewable energy injection on system reliability is investigated us-ing RBSA. A robust RBSA diagnostics tool is developed which provides an interactive user interface where the RBSA results and contingency ranking reports can be explored and compared based on specific user inputs without executing time domain simulations or risk calculations, hence providing a fast and robust approach for handling large time domain simulation and risk assessment data. The results show that RBSA can be used effectively in system planning to select security limits. Comparison of RBSA with deterministic methods show that RBSA not only provides less conservative results, it also illustrates the bases on which such security decisions are made. RBSA helps in identifying critical aspects of system reliability that is not possible using the deterministic reliability techniques. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017

Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-22Bitstream added on 2014-06-13T18:49:40Z : No. of bitstreams: 1 pereira_mbc_me_ilha.pdf: 1170771 bytes, checksum: f8ba8678a1d9af0316e036187c7f36d7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho tem por objetivo contribuir para o desenvolvimento de técnicas de Educação em Engenharia apresentando uma ferramenta de apoio ao Ensino/Aprendizagem de Sistemas Elétricos de Potência na forma de um software de interface amigável e baixo custo. O software desenvolvido em linguagem C++ segue os padrões de programação orientada a objetos e oferece ao usuário a resolução de fluxos de potência e simulações de casos de contingências transitórias com possibilidade de interatividade, apresentando resultados em ambiente gráfico. Desenvolvido para aplicação na área de Dinâmica e Estabilidade de Sistemas de Potência, suporta sistemas-exemplos clássicos do IEEE e também disponibiliza ao usuário ferramentas para personalização de arquivos de dados de entrada, tornando-se flexível e de fácil acesso aos casos já inseridos no sistema. O usuário também pode criar novos sistemas de acordo com suas necessidades. Os resultados são exibidos em forma numérica e também através de gráficos tridimensionais e animação, possibilitando fácil visualização de resultados, entendimento de fenômenos e análise de influências sobre o desempenho. / This work presents a contribution to the development of Engineering Education techniques by means of a Teaching/Learning support tool for Electrical Power System studies resulting in a friendly low cost interface software. It was developed in C++ language and follows the pattern of object oriented programming, offering to the user the resolution of load flow and digital simulations of transient stability with the possibility of interactivity, showing the results in a graphic environment. It was developed for use in applications of Static and Transient Power Systems Stability and it has enclosed classic sample-systems of IEEE and others and also allows the user to customize input data files. Then the tool is flexible and enables easy access to cases formerly inserted in the system. The user also can create new systems according to his needs. The machines rotors movement can be seen in a graphic animation, allowing easy visualization of events, phenomena comprehension and analysis of influences about the performance.

Orientador: Laurence Duarte Colvara / Banca: Sergio Azevedo de Oliveira / Banca: Silvia Galvão de Souza Cervantes / Resumo: Este trabalho tem por objetivo contribuir para o desenvolvimento de técnicas de Educação em Engenharia apresentando uma ferramenta de apoio ao Ensino/Aprendizagem de Sistemas Elétricos de Potência na forma de um software de interface amigável e baixo custo. O software desenvolvido em linguagem C++ segue os padrões de programação orientada a objetos e oferece ao usuário a resolução de fluxos de potência e simulações de casos de contingências transitórias com possibilidade de interatividade, apresentando resultados em ambiente gráfico. Desenvolvido para aplicação na área de Dinâmica e Estabilidade de Sistemas de Potência, suporta sistemas-exemplos clássicos do IEEE e também disponibiliza ao usuário ferramentas para personalização de arquivos de dados de entrada, tornando-se flexível e de fácil acesso aos casos já inseridos no sistema. O usuário também pode criar novos sistemas de acordo com suas necessidades. Os resultados são exibidos em forma numérica e também através de gráficos tridimensionais e animação, possibilitando fácil visualização de resultados, entendimento de fenômenos e análise de influências sobre o desempenho. / Abstract: This work presents a contribution to the development of Engineering Education techniques by means of a Teaching/Learning support tool for Electrical Power System studies resulting in a friendly low cost interface software. It was developed in C++ language and follows the pattern of object oriented programming, offering to the user the resolution of load flow and digital simulations of transient stability with the possibility of interactivity, showing the results in a graphic environment. It was developed for use in applications of Static and Transient Power Systems Stability and it has enclosed classic sample-systems of IEEE and others and also allows the user to customize input data files. Then the tool is flexible and enables easy access to cases formerly inserted in the system. The user also can create new systems according to his needs. The machines rotors movement can be seen in a graphic animation, allowing easy visualization of events, phenomena comprehension and analysis of influences about the performance. / Mestre

Made available in DSpace on 2014-12-17T14:55:57Z (GMT). No. of bitstreams: 1 ClovisBMO.pdf: 4499915 bytes, checksum: b3ed589a5cb7e5f7a1b113d606f615e2 (MD5) Previous issue date: 2006-02-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work presents a description of models development at DigSILENT PowerFactoryTM program for the transient stability study in power systems with wind turbine. The main goal is to make available means to use a dynamic simulation program in power systems, widely published, and utilize it as a tool that helps in programs results evaluations used for this intent. The process of simulations and analyses results starts after the models setting description phase. The results obtained by the DigSILENT PowerFactoryTM and ATP, program chosen to the validation also international recognized, are compared during this phase. The main tools and guide lines of PowerFactoryTM program use are presented here, directing these elements to the solution of the approached problem. For the simulation it is used a real system which it will be connected a wind farm. Two different technologies of wind turbines were implemented: doubly-fed induction generator with frequency converter, connecting the rotor to the stator and to the grid, and synchronous wind generator with frequency converter, interconnecting the generator to the grid. Besides presenting the basic conceptions of dynamic simulation, it is described the implemented control strategies and models of turbine and converters. The stability of the wind turbine interconnected to grid is analyzed in many operational conditions, resultant of diverse kinds of disturbances / Este trabalho apresenta uma descri??o do desenvolvimento de modelos no programa DigSILENT PowerFactoryTM voltados ao estudo de estabilidade transit?ria em sistemas de pot?ncia com aerogerador. O objetivo ? disponibilizar meios para se utilizar um programa de simula??o din?mica em sistemas de pot?ncia, amplamente divulgado, e utiliz?-lo como uma ferramenta que auxilie na avalia??o dos resultados de programas usados para este fim. Ap?s a fase de descri??o da montagem dos modelos inicia-se o processo de simula??o e an?lise dos resultados. ? durante esta fase que s?o comparados os resultados do DigSILENT PowerFactoryTM com os resultados obtidos com o ATP, programa escolhido para avalia??o, tamb?m com reconhecimento internacional. S?o apresentadas as principais ferramentas e diretrizes do uso do programa PowerFactoryTM, direcionando tais elementos ? solu??o do problema formulado. Para simula??o, utiliza-se uma rede real, na qual ser? introduzido um parque e?lico. Dois tipos de tecnologias de gera??o e?lica foram implementadas: aerogerador de indu??o duplamente excitado com conversor de freq??ncia, conectando o rotor ao estator e ? rede, e aerogerador s?ncrono com conversor de freq??ncia, interligando o gerador ? rede. Al?m de apresentar os conceitos b?sicos de simula??o din?mica, descrevem-se as estrat?gias de controle implementadas e os modelos de turbinas e conversores. A estabilidade do aerogerador interligado ? rede ? avaliada em diversas condi??es operacionais, resultante de variados tipos de perturba??es

Nesta pesquisa são analisados os mecanismos que levam um sistema elétrico de potência (SEP) à instabilidade proveniente de uma perturbação de grande porte e as formas de se avaliar diretamente a margem de estabilidade desse sistema quando o mesmo é modelado preservando a estrutura da rede de transmissão. O sistema foi matematicamente modelado por um conjunto de equações algébrico-diferenciais (EAD), que permite modelagens mais compreensivas da carga e da rede e possibilita melhor avaliação da estabilidade de um sistema quando comparado com o modelo de equações diferenciais ordinárias (EDO) utilizado tradicionalmente para o estudo de estabilidade transitória. A avaliação direta da margem de estabilidade do sistema de potência modelado por conjuntos de EAD foi realizada usando métodos diretos de análise com base no conceito de ponto de equilíbrio instável de controle (PEIC). Tais métodos permitem a obtenção da margem deforma local e rápida, sem requerer a integração numérica de equações diferenciais do modelo pós-falta. No entanto, existem alguns problemas abertos para se alcançar a completa fundamentação do método PEIC para modelos de EAD. Assim, neste estudo dá-se um passo nesta direção, mostrando que as definições existentes de PEIC e de outros pontos de interesse podem ser falhas, principalmente quando a trajetória de falta do sistema alcança superfícies singulares. Neste sentido, são propostos a correção destas definições e um método direto de detecção do PEIC. O método proposto é adequado para análise direta de estabilidade angular e de tensão de curto-termos devido a grandes perturbações e capaz de fornecer corretos tempos críticos de abertura e a identificação dos mecanismos de instabilização do sistema de EAD, mesmo quando as trajetórias do sistema alcançam superfícies singulares. / This thesis addresses to the mechanisms that lead an electric power system to instability due to large disturbances and to the methods to assess directly the stability margin when the system is modeled preserving the network structure. The system is modeled by a set of differential-algebraic equations (DAE) that permits more comprehensive models for the load and network and provides a better stability margin assessment when compared to the model of ordinary differential equations (ODE) traditionally used for transient stability analysis. The direct assessment of the stability margin was realized using direct methods based on the controlling unstable equilibrium point (CUEP) concept and permits to assess the margin in a local and fast manner, without requires the time integration of the post-fault system differential equations. Nevertheless, some open problems remain to be solved in order to provide a complete foundation of the CUEP method for DAE power system models. In this research a further step is given in this direction, showing that the existent definitions for the CUEP and other interest points may fail, mainly when the fault-on trajectory reaches singular surfaces. In this sense, it is proposed the correction of these definitions and a new CUEP method that is adequate to the angular and voltage short-term direct stability assessment due to large disturbances; capable to provide precise critical clearing times and the identification of the instability mechanisms for the DAE modeled power system, even in the presence of singular surfaces.

[pt] A metodologia empregada para o cálculo de equivalentes dinâmicos apresenta três etapas essenciais: a identificação de geradores coerentes, a redução estática da rede e a agregação dinâmica dos modelos das unidades geradoras coerentes. Dentre essas etapas, a última é a que menos tem sido tratada, e que vem requerendo maior desenvolvimento. Esta dissertação trata do problema da agregação dinâmica de modelos de sistemas de excitação de geradores coerentes, visando o cálculo de equivalentes dinâmicos para estudos de estabilidade transitória de sistemas de energia elétrica. O principal objetivo é a determinação de um critério de escolha do melhor modelo equivalente para uma dada composição de modelos de sistemas de excitação num grupo de geradores coerentes. Os parâmetros dos modelos equivalentes dos sistemas de excitação dos grupos de unidades geradoras coerentes são ajustados numericamente a partir das respostas em frequência dos modelos individuais de cada grupo, utilizando-se o método de Levenberg-Marquardt, o que caracteriza um problema de otimização multivariável. Os desempenhos dinâmicos dos equivalentes propostos são avaliados em um sistema teste. / [en] The methodology used to calculate dynamic equivalents has three basic steps: the identification of the coherent groups of generating units, the network reduction and the dynamic aggregation of coherent generator models. Among these steps, the last one has not been studied lately and deserves more development. This disseration deals with the problem of dynamic aggregation of excitaion system models to calculate coherency-based dynamic equivalents for power system transient stability studies. The main objective is the determination of a criteria to choose the best equivalent model for a given composition of excitation system models in a group of coherent generators. The parameters of the excitation system equivalent model for cach group of coherent generating units are numerically adjusted to match the frequency response of the individual models. This is a multivariable otmization problem, which is solved using the Levenberg-Marquardt method. The dynamic performance of the proposed equivalents is evaluated in a test system.

Les systèmes électriques évoluent actuellement vers l'intégration d'une production moins carbonée, éventuellement plus locale. Afin d’explorer les évolutions possibles de ces systèmes sur le long terme, l’exercice prospectif s’appuyant sur des modèles est un outil précieux. Cependant, pour être pertinent, il doit réconcilier des phénomènes spatiaux et temporels à des échelles variées. Ainsi, le fonctionnement du système électrique repose sur un équilibre offre – demande à chaque instant. Afin de corriger les fluctuations de la production ou de la consommation qui surviennent nécessairement, les gestionnaires de réseau mettent en place un certain nombre de régulations dont les durées d’activation sont de l’ordre de quelques secondes à quelques heures. A des échelles de temps encore plus fines le système électrique présente une robustesse interne : le réseau électrique créé un couplage électromagnétique entre les machines synchrones qui leur permet de mutualiser leur inertie respective. Cette inertie, qui constitue une réserve d’énergie cinétique, est instantanément disponible pour faire face aux fluctuations. Pour que les scénarios de long terme proposés ne soient pas en contradiction avec les exigences de robustesse du système électrique, qui permettront son opération, il est nécessaire que l’évaluation de cette robustesse soit intégrée à la modélisation prospective. Dans ce travail, nous proposons un indicateur, calculable au sein des études de prospective, qui évalue la stabilité d’un système électrique, c’est- à-dire son aptitude à revenir au synchronisme suite à une perturbation. Cet indicateur repose sur une description agrégée du réseau de transport et traduit le couplage électromagnétique apporté par le réseau. Associé au modèle bottom-up de la famille MARKAL/TIMES décrivant le système électrique français, cet indicateur de synchronisme et un indicateur quantifiant la réserve cinétique disponible, nous permet d’évaluer les conséquences de la pénétration du renouvelable, notamment sur la robustesse du système électrique. / Power systems are currently facing several issues in order to evolve and integrate less carbon-heavy, and potentially more local, production. Prospective model-based analysis is a precious tool for exploring the possible long-term developments of these systems and comparing their advantages and disadvantages. However, to ensure relevance, it is important to reconcile the spatial and temporal phenomena that occur at various scales. Power system management depends on constantly maintaining a complex supply- demand balance. Meeting this challenge requires anticipating demand variations and power plant availability, combined with regulation systems to resolve remaining discrepancies. These regulations are activated in from a few seconds up to several hours. On shorter timescales, power systems show inherent robustness: the power grid creates an electromagnetic coupling between synchronous machines allowing them to share their inertia. This inertia, which takes the form of kinetic energy, is instantaneously available to face natural demand or supply fluctuations. To ensure that proposed long-term scenarios are consistent with the robustness requirements of power systems, which enable their management, this robustness must be assessed using prospective modeling. In this work, we propose an indicator, calculable within prospective studies, which assesses power system stability, namely its ability to return to synchronism after a perturbation. This indicator is based on an aggregated description of the transportation power grid and describes the electromagnetic coupling brought by the power grid. When combined with a bottom-up model from the MARKAL/TIMES family describing the French power system, this synchronism indicator, along with another indicator quantifying the available kinetic reserve, enables us to assess the consequences of renewable penetration, especially in terms of power system robustness.