This thesis is dedicated to a comprehensive study of static series synchronous compensator (SSSC) systems utilizing cascaded-multilevel converters (CMCs). Among flexible AC transmission system (FACTS) controllers, the SSSC has shown feasibility in terms of cost-effectiveness in a wide range of problem-solving abilities from transmission to distribution levels. Referring to the literature reviews, the CMC with separated DC capacitors is clearly the most feasible topology for use as a power converter in the SSSC applications. The control for the CMC-Based SSSC is complicated. The design of the complicated control strategy was begun with well-defined system transfer functions. The stability of the system was achieved by trial and error processes, which were time-consuming and ineffective. The goal of this thesis is to achieve a reliable controller design for the CMC-based SSSC. Major contributions are addressed as follows: 1) accurate models of the CMC for reactive power compensations in both ABC and DQ0 coordinates, and 2) an effective decoupling power control technique. To simplify the control system design, well-defined models of the CMC-Based SSSC in both ABC and DQ0 coordinates are proposed. The proposed models are for the CMC-Based SSSC focus on only three voltage levels but can be expanded for any number of voltage levels. The key system transfer functions are derived and used in the controller design process. To achieve independent power control capability, the control technique, called the decoupling power control used in the design for the CMC-Based STATCOM is applied. This control technique allows both the real and reactive power components to be independently controlled. With the combination of the decoupling power control and the cascaded PWM, a CMC with any number of voltage levels can be simply modeled as a three-level cascaded converter, which is the simplest topology to deal with. This thesis focuses on the detailed design process needed for a CMC-Based SSSC. / Master of Science

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-19T19:42:59Z No. of bitstreams: 1 danielsalomaosilva.pdf: 1815639 bytes, checksum: 1ac9991f1cfff85fc90c22c80f5ccaf4 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-20T13:12:33Z (GMT) No. of bitstreams: 1 danielsalomaosilva.pdf: 1815639 bytes, checksum: 1ac9991f1cfff85fc90c22c80f5ccaf4 (MD5) / Made available in DSpace on 2017-04-20T13:12:33Z (GMT). No. of bitstreams: 1 danielsalomaosilva.pdf: 1815639 bytes, checksum: 1ac9991f1cfff85fc90c22c80f5ccaf4 (MD5) Previous issue date: 2011-09-01 / O Compensador Série Síncrono Estático (SSSC – Static Synchronous Series Compensator) é um controlador FACTS (Flexible AC Transmission Systems) proposto na literatura para controlar o fluxo de potência pelas linhas de transmissão a corrente alternada. O SSSC é um compensador de potência reativa baseado em conversores eletrônicos de potência de alta capacidade ligados em série com as linhas de transmissão. Neste trabalho são utilizados conversores fonte de tensão (do inglês, VSC – Voltage Source Converters) multiníveis em cascata assimétrica, ligados ao sistema elétrico sem transformadores. O uso do SSSC aumenta as margens de estabilidade, a controlabilidade e a capacidade de transferência de potência de um sistema elétrico. Como a tensão sintetizada pelo SSSC está em quadratura com a corrente pela linha, pode-se utilizá-lo para emular uma reatância série, impor uma tensão ou injetar/absorver potência reativa em série com a linha de transmissão compensada. Neste trabalho são estudados cinco diferentes algoritmos para controlar as tensões geradas pelo SSSC. Resultados de simulações digitais são utilizados para verificar o desempenho de cada algoritmo implementado. / The Static Synchronous Series Compensator (SSSC) is a FACTS (Flexible AC Transmission Systems) controller proposed in the literature to control the power flow through the transmission power lines. The SSSC is a series connected compensator based on static power electronics converters. In this work, three single-phase asymmetrical cascaded multilevel voltage source converters (VSC) are used, connected to the electric power system without transformers. The use of SSSC increases the stability limit, the controllability and the transfer power capacity of electric power systems. Since the voltage synthesized by SSSC is in quadrature with line current, it can be used to emulate a series reactance, to synthesize a voltage or to inject/absorb reactive power in series with the compensated transmission line. Five different control algorithms are investigated to control the output voltages of the SSSC. Digital simulation results are used to demonstrate the effectiveness of each control strategy.

Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-19Bitstream added on 2014-06-13T18:49:32Z : No. of bitstreams: 1 menezes_mm_me_ilha.pdf: 769292 bytes, checksum: 4b80be15a6104228fa9612312498644f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho apresenta estudos referentes à estabilidade a pequenas perturbações do SEP, considerando a atuação de FACTS para o amortecimento das oscilações eletromecânicas de baixa frequência. São abordados os dispositivos FACTS TCSC (Thyristor Controlled Series Capacitor) e o SSSC (Static Synchronous Series Compensator). É realizada a representação e modelagem dos dispositivos FACTS no SEP inserindo no Modelo Sensibilidade de Potência. Para melhorar o desempenho do SEP no que se refere à estabilidade a pequenas perturbações, controladores suplementares são propostos para aumentar o desempenho dos dispositivos TCSC e SSSC, introduzindo o amortecimento necessário ao SEP. Adicionam-se os controladores suplementares POD no modelo modificado para os dispositivos TCSC e SSSC para verificar sua atuação. Para encontrar a melhor localização para instalação dos dispositivos é usado a teoria dos resíduos. Esta mesma teoria é usada também para o ajuste dos parâmetros dos controlares juntamente com outro ajuste feito através de Redes Neurais Artificiais (RNA), que é proposto como alternativa de comparação ao método dos resíduos. Simulações são efetuadas em um sistema teste simétrico para se verificar resultados e a eficácia do controlador POD (parâmetros ajustados pela RNA proposta), acoplados aos dispositivos FACTS, na manutenção da estabilidade a pequenas perturbações do SEP. Palavras-chave: Controladores POD. Estabilidade de sistema de potência. Redes neurais artificiais. TCSC e SSSC / This work presents studies referred to short term Electric Power System (EPS) perturbations, considering the actuation of FACTS devices for low frequency electromechanical oscillation damping. The devices considered are: FACTS TCSC (Thyristor Controlled Series Capacitor) and the SSSC (Static Synchronous Series Compensator). It is representation and modeling FACTS devices in the EPS inserting in the Power Sensitivity Model. To improve the performance of the EPS considering the short term perturbations, additional controllers are proposed to increase the performance of the TCSC and SSSC devices, introducing the necessary damping to the EPS. The additional POD controller is added to the modified model for TCSC and SSSC devices to verify the acting. The residual theory is used to find the best location to install the devices. The same theory is used to adjust the parameters of the controllers and an adjustment with Artificial Neural Networks (ANN) is proposed as an alternative to the residual method. Simulations are effectuated for a symmetric test system to verify the efficiency of the POD controller (parameters adjusted by the ANN proposed), coupled with the FACTS devices, to maintain the stability considering the short term perturbations

Dans ce travail, la stabilité transitoire et l'amortissement des oscillations dans les réseaux électriques sont améliorés en utilisant la commande en ligne du SMES (Superconducting Magnetic Energy Storage) et du SSSC (Static Synchronous Séries Compensator). Les commandes proposées sont basées sur la théorie de la logique floue. Dans le cas du SSSC, elle est associée à la fonction d'énergie transitoire. Nous avons également associé une loi de type mode glissant pour éliminer le lien hors ligne entre la commande du SMES et le centre de contrôle des réseaux. Ceci permet un maintien du fonctionnement du régulateur en l'absence.de phase d'apprentissage. Le SMES et le SSSC sont connectés à un point intermédiaire d'une longue ligne qui relie deux parties du réseau. Une réalisation pratique du régulateur à été étudie et les mesures nécessaires pour la commande peuvent s'obtenir à partir du noeud auquel est connecté le régulateur. Afin de valider les commandes proposées, celles-ci ont été implanté en simulation sur deux exemples de réseaux : un réseau comportant une ligne et le réseau de New England. Les résultats obtenues montrent une amélioration considérable du temps critique d'élimination du défaut ainsi que l'amortissement des oscillations après le défaut. Notre méthode a également apporté une augmentation de la capacité de transfert correspondant aux lignes de transmission.

Η εργασία πραγματεύεται την απόσβεση των ταλαντώσεων ισχύος με χρήση του εξελιγμένου ελεγχόμενου αντισταθμιστή σειράς. / SSSC is used in order to improve power system oscillation stability and some useful analytical conclusions are presented.

Orientador: Percival Bueno de Araujo / Banca: Anna Diva Plasencia Lotufo / Banca: George Lauro Ribeiro de Brito / Resumo: Este trabalho apresenta estudos referentes à estabilidade a pequenas perturbações do SEP, considerando a atuação de FACTS para o amortecimento das oscilações eletromecânicas de baixa frequência. São abordados os dispositivos FACTS TCSC (Thyristor Controlled Series Capacitor) e o SSSC (Static Synchronous Series Compensator). É realizada a representação e modelagem dos dispositivos FACTS no SEP inserindo no Modelo Sensibilidade de Potência. Para melhorar o desempenho do SEP no que se refere à estabilidade a pequenas perturbações, controladores suplementares são propostos para aumentar o desempenho dos dispositivos TCSC e SSSC, introduzindo o amortecimento necessário ao SEP. Adicionam-se os controladores suplementares POD no modelo modificado para os dispositivos TCSC e SSSC para verificar sua atuação. Para encontrar a melhor localização para instalação dos dispositivos é usado a teoria dos resíduos. Esta mesma teoria é usada também para o ajuste dos parâmetros dos controlares juntamente com outro ajuste feito através de Redes Neurais Artificiais (RNA), que é proposto como alternativa de comparação ao método dos resíduos. Simulações são efetuadas em um sistema teste simétrico para se verificar resultados e a eficácia do controlador POD (parâmetros ajustados pela RNA proposta), acoplados aos dispositivos FACTS, na manutenção da estabilidade a pequenas perturbações do SEP. Palavras-chave: Controladores POD. Estabilidade de sistema de potência. Redes neurais artificiais. TCSC e SSSC / Abstract: This work presents studies referred to short term Electric Power System (EPS) perturbations, considering the actuation of FACTS devices for low frequency electromechanical oscillation damping. The devices considered are: FACTS TCSC (Thyristor Controlled Series Capacitor) and the SSSC (Static Synchronous Series Compensator). It is representation and modeling FACTS devices in the EPS inserting in the Power Sensitivity Model. To improve the performance of the EPS considering the short term perturbations, additional controllers are proposed to increase the performance of the TCSC and SSSC devices, introducing the necessary damping to the EPS. The additional POD controller is added to the modified model for TCSC and SSSC devices to verify the acting. The residual theory is used to find the best location to install the devices. The same theory is used to adjust the parameters of the controllers and an adjustment with Artificial Neural Networks (ANN) is proposed as an alternative to the residual method. Simulations are effectuated for a symmetric test system to verify the efficiency of the POD controller (parameters adjusted by the ANN proposed), coupled with the FACTS devices, to maintain the stability considering the short term perturbations / Mestre

Orientador: Percival Bueno de Araujo / Resumo: Neste trabalho é desenvolvido o modelo matemático de sistemas elétricos de potência multimáquinas para avaliar a estabilidade a pequenas perturbações, com a atuação simultânea de diferentes dispositivos FACTS controlando o fluxo de potência. Os FACTS do tipo SSSC e STATCOM são modelados, considerando suas perdas internas, o modelo resultante é acrescentado à resolução do fluxo de potência, considerando que cada dispositivo FACTS controla uma grandeza do sistema. Utilizando da solução do fluxo, das matrizes Ybarra e Jacobiana, e também tensões e potências, estes são empregados ao Modelo de Sensibilidade de Potência, por meio de simulações, é verificada a atuação dos elementos de controle na estabilidade a pequenas perturbações de sistemas multimáquinas. Para acréscimo de amortecimento às oscilações eletromecânicas, são aplicados controladores ESP e POD. A partir da representação de espaço de estados do modelo final, os autovalores resultantes são estudados para avaliar a estabilidade do sistema. Ao final é discutida a atuação individual e conjunta dos dispositivos FACTS na estabilidade, quando aplicados ao controle do fluxo de potência. / Abstract: In this work the mathematical model of multi-machine power electric systems is developed to evaluate the stability to small perturbations, with the simultaneous actuation of different FACTS devices controlling the power flow. The FACTS of type SSSC and STATCOM are modeled, considering their internal losses, the resulting model is added to the resolution of the power flow, considering that each FACTS device controls a quantity of the system. By the solution of the power flux, the Ybus and Jacobian matrices, as well as voltages and powers, these are used to the Power Sensitivity Model, by means of simulations, it is verified the performance of the control elements in the stability to small perturbation of multi-machine systems. For addition of damping to electromechanical oscillations, ESP and POD controllers are applied. From the state space representation of the final model, the resulting eigenvalues are studied to evaluate the stability of the system. At the end, the individual and combined performance of the FACTS devices in the stability, when applied to the control of the power flow, is discussed. / Doutor

In order to identify the weakest bus in a power system so that the Unified Power Flow Controller could be connected, an investigation of static and dynamic voltage stability is presented. Two stability indices, static and dynamic, have been proposed in the thesis. Multi-Input Multi-Output (MIMO) analysis has been used for the dynamic stability analysis. Results based on the Western System Coordinate Council (WSCC) 3-machine, 9-bus test system and IEEE 14 bus Reliability Test System (RTS) shows that these indices detect with the degree of accuracy the weakest bus, the weakest line and the voltage stability margin in the test system before suffering from voltage collapse. Recently, Flexible Alternating Current Transmission systems (FACTs) have become significant due to the need to strengthen existing power systems. The UPFC has been identified in literature as the most comprehensive and complex FACTs equipment that has emerged for the control and optimization of power flow in AC transmission systems. Significant research has been done on the UPFC. However, the extent of UPFC capability, connected to the weakest bus in maintaining the power flows under fault conditions, not only in the line where it is installed, but also in adjacent parallel lines, remains to be studied. In the literature, it has normally been assumed the UPFC is disconnected during a fault period. In this investigation it has been shown that fault conditions can affect the UPFC significantly, even if it occurred on far buses of the power system. This forms the main contribution presented in this thesis. The impact of UPFC in minimizing the disturbances in voltages, currents and power flows under fault conditions are investigated. The WSCC 3-machine, 9-bus test system is used to investigate the effect of an unsymmetrical fault type and position on the operation of UPFC controller in accordance to the G59 protection, stability and regulation. Results show that it is necessary to disconnect the UPFC controller from the power system during unsymmetrical fault conditions.

No description available.

With limited enhancement or expansion of the transmission infrastructure, the contemporary power systems are operating under more stressed conditions. It becomes important to fully utilize the existing transmission system to supply load demand as much as possible, thus eliminating or reducing the need for new transmission investment. Flexible AC Transmission System (FACTS) technology provides an alternative to fully utilize the existing transmission lines as well as new and upgraded lines, by controlling power and also enhancing the power transfer capability of transmission lines. However, the implementation of FACTS controllers in the transmission system has introduced new power system dynamics that must be addressed in the area of power system protection, such as rapid changes in line impedance, power angle, line currents, transients introduced by the occurrence of fault and associated control action of the FACTS controller. Therefore, the performance of the protection system must be carefully analyzed in the presence of FACTS controllers. The thesis aims at evaluating the performance of distance relays when different types of FACTS controllers, in particular Voltage Source Converter (VSC) based FACTS controllers, are incorporated at the midpoint of the transmission system to achieve voltage profile improvement and power transfer capability. The detailed models of these controllers and their control strategies are described. The presence of FACTS controllers in the loop affects both steady state and transient components of voltage and current signals. The rapid response of FACTS controllers to different power system configurations significantly affects the apparent impedance seen by distance relays. The apparent impedance seen by distance relays would be different from that of the system without FACTS controller. Due to this, the distance relay may malfunction, resulting in unreliable operation of the power system during faults. Furthermore, the effect of FACTS controllers on distance relay operation depends on the type of FACTS controller used, the application for which it has been installed and its location in the power system. The distance relay is evaluated for different loading conditions and for various fault conditions. Simulation studies are carried out using PSCAD/EMTDC based transient simulation package.