The objective of this thesis is to investigate the transient response and optimal economic dispatch of an isolated power system with wind generators. Different types of wind turbines and the classification of Stability are introduced. Then, the process of Transient stability analysis and the concept of Genetic Algorithms are given for explanation. In this thesis, the practical power system of Kinmen is selected for case study. The disturbances introduced by gusting wind and N-1 system contingency are considered in the transient stability analysis. Furthermore, in order to obtain both accuracy and feasibility of the Optimal power dispatch by using Real-parameter Genetic Algorithms, the simulation results should be tested for the restrictions and requirements of the actual operation.

[pt] O presente trabalho de dissertação de mestrado tem por finalidade contribuir para uma maior dinamização do ensino de engenharia de sistemas de potência através da elaboração de um conjunto de algoritmos interativos para microcomputadores, onde o aluno poderá realizar um processo contínuo de experimentação, questionamento e revisão de conceitos. Para um bom desenvolvimento deste processo de aprendizagem é criado um ambiente amigável onde o usuário tem suas ações amparadas por mensagens explicativas e de monitoração de erros, resultando na redução do tempo gasto em cada seção de estudo e estimulando o mesmo a realizar um número maior de simulações. Foram elaboradas quatro programas de computadores. O primeiro, responsável pela estrutura conversacional e gerenciamento, foi escrito em PASCAL. Os demais foram escritos em FORTRAN77 e se restringem à execução dos cálculos necessários aos estudos de: fluxo de potência, curto-circuito e estabilidade transitória. Estes três últimos programas utilizam técnicas especiais para armazenagem de matrizes esparsas e obtenção do elementos de interesse de suas inversas. Três sistemas de potência foram escolhidos para estar imediatamente disponíveis ao usuário, sendo que um deles é utilizado no texto durante a explanação da estrutura conversacional para os estudos disponíveis. / [en] The present Dissertation aims to provide more dynamism to the teaching and learning process in power system engineering through a set of interactive personal computer algorithms. The student may carry out a continuous process of experimenting, questioning and revision of concepts. In order to better develop the leaining process, a frindly environment is created where the user has his actions supported by explanatory and error monitoring messages. This results in a reduction of the time spent in each study section and, consequently, it estimulates the student to perform a greater number of simulations. Four computer programs have been developed. There is one written in PASCAL language, responsible for the following studies: load flow, slort-circuit and transient stability. These programs use special sparsity techniques and programming. Three power systems have been choosen to be immediately available to the user. One of them is used in the text during the explanation process of the conversational structure of the power system studies.

This thesis introduces a new modeling approach that allows very large power systems to be modeled on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs. The key step in achieving this is the development of an improved wide-band multi-port equivalent, which reduces a large power network into a small manageable equivalent model that preserves wideband behaviors. This approach has a foundation method that use a two part equivalent in which the high frequency behavior of the equivalenced network is represented by a terminating frequency dependent network equivalent (FDNE), with the low frequency behavior being modeled using a detailed Transient Stability Analysis (TSA) model that only models the electromechanical behavior. This approach allowed the modelling of medium size electric regions up to hundreds of buses in real time. This thesis extends the equivalent by implementing a reduced order of the detailed electromechanical TSA equivalent mentioned above. Coherency based reduction is used for the electromechanical model of the power network to be equivalenced, and is implemented as a Transient Stability Analysis (TSA) type electromechanical equivalent. A challenge in implementing the FDNE is to ensure that it is a passive network, as otherwise its inclusion could lead to unstable simulation. This thesis also introduces a practical procedure to enforce passivity in the FDNE. The validity of the proposed technique is demonstrated by comparing the approach with detailed electromagnetic simulations of the well-known 39 bus New England system and a modified 39 bus system with an HVDC infeed with coupling between the dc line and an adjacent ac line, in addition to a 108 bus ac system. The power of the method is demonstrated by the real-time simulation of a large system with 2300 busses and 139 generators. It has been shown that this approach has the potential to increase by at least one order of magnitude the size of the network that can be modeled and thus on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs.

This thesis presents a transient stability method using dynamic phasors. This method can be used to investigate low frequency (<5Hz) and sub-synchronous frequency (5Hz-60Hz) oscillations. It has major advantages as compared to traditional transient stability method and EMT method. It allows modeling of higher-frequency oscillation possible using time domain simulations, which is not achievable with conventional method. It also can be simulated at much larger time step as compared to PSCAD/EMTDC simulation. Comparison of the results with traditional model and detailed EMT model are also present, and they show very accurate results at frequency ranges up to 60Hz.

This thesis introduces a new modeling approach that allows very large power systems to be modeled on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs. The key step in achieving this is the development of an improved wide-band multi-port equivalent, which reduces a large power network into a small manageable equivalent model that preserves wideband behaviors. This approach has a foundation method that use a two part equivalent in which the high frequency behavior of the equivalenced network is represented by a terminating frequency dependent network equivalent (FDNE), with the low frequency behavior being modeled using a detailed Transient Stability Analysis (TSA) model that only models the electromechanical behavior. This approach allowed the modelling of medium size electric regions up to hundreds of buses in real time. This thesis extends the equivalent by implementing a reduced order of the detailed electromechanical TSA equivalent mentioned above. Coherency based reduction is used for the electromechanical model of the power network to be equivalenced, and is implemented as a Transient Stability Analysis (TSA) type electromechanical equivalent. A challenge in implementing the FDNE is to ensure that it is a passive network, as otherwise its inclusion could lead to unstable simulation. This thesis also introduces a practical procedure to enforce passivity in the FDNE. The validity of the proposed technique is demonstrated by comparing the approach with detailed electromagnetic simulations of the well-known 39 bus New England system and a modified 39 bus system with an HVDC infeed with coupling between the dc line and an adjacent ac line, in addition to a 108 bus ac system. The power of the method is demonstrated by the real-time simulation of a large system with 2300 busses and 139 generators. It has been shown that this approach has the potential to increase by at least one order of magnitude the size of the network that can be modeled and thus on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study had as main objective to perform the modeling and analysis of transient stability of a typical electric power system. The second goal, also important, was to assess the feasibility of using ATP (Alternative Transients Program) as a computer tool for simulation of transient stability. The system focused here is comprised of nine busses with three generators, one hydraulic and the other two with thermal characteristics. All the system machines were equipped with voltage regulators and speed governor in ATP software. The technical issues studied here refer to the analysis of system stability after a disturbance, such as: three-phase short-circuit, load loss and generation outage. The results show that ATP software performs satisfactorily the transient stability analysis. This fact can also be proved by comparing the results obtained from ATP with those from simulations with PSAT (Power System Analysis Toolbox). For this purpose some adjustments were necessary in the graphical results since ATP works in time domain while PSAT program operates in the frequency domain. / Este trabalho teve como principal objetivo realizar a modelagem e a análise da estabilidade transitória de um sistema elétrico de potência típico. O segundo objetivo, também importante, consistiu em avaliar a viabilidade de se utilizar o ATP (Alternative Transients Program) como uma ferramenta computacional para simulação de estabilidade transitória. O sistema aqui enfocado é composto por nove barramentos com três unidades geradoras, uma com característica hidráulica e as outras duas com características térmicas. Todas as máquinas do sistema foram equipadas com reguladores de tensão e velocidade no programa ATP. As questões técnicas estudadas aqui se referem à análise da estabilidade do sistema após uma perturbação, sendo elas: falta trifásica, perda de carga e saída de geração. Os resultados mostram que o software ATP realiza satisfatoriamente a análise de estabilidade transitória. Este fato pode também ser comprovado pela comparação dos resultados obtidos com o ATP com aqueles provenientes de simulações com o PSAT (Power System Analysis Toolbox). Para este propósito foi necessário realizar alguns ajustes nos resultados gráficos já que ATP trabalha no domínio do tempo enquanto que o programa PSAT opera no domínio da frequência, tais como: transformação de alguns gráficos fornecidos pelo ATP em pu. / Mestre em Ciências