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Gianto, Rudy. "Coordination of power system controllers for optimal damping of electromechanical oscillations." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0056.
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This thesis is devoted to the development of new approaches for control coordination of PSSs (power system stabilisers) and FACTS (flexible alternating current transmission system) devices for achieving and enhancing small-disturbance stability in multi-machine power systems. The key objectives of the research reported in the thesis are, through optimal control coordination of PSSs and/or FACTS devices, those of maintaining satisfactory power oscillation damping and secure system operation when the power system is subject to persisting disturbances in the form of load demand fluctuations and switching control. Although occurring less frequently, fault disturbances are also considered in the assessment of the control coordination performance. Based on the constrained optimisation method in which the eigenvalue-based objective function is minimised to identify the optimal parameters of power system damping controllers, the thesis first develops a procedure for designing the control coordination of PSSs and FACTS devices controllers. The eigenvalue-eigenvector equations associated with the selected electromechanical modes form a set of equality constraints in the optimisation. The key advance of the procedure is that there is no need for any special software system for eigenvalue calculations, and the use of sparse Jacobian matrix for forming the eigenvalue-eigenvector equations leads to the sparsity formulation which is essential for large power systems. Inequality constraints include those for imposing bounds on the controller parameters. Constraints which guarantee that the modes are distinct ones are derived and incorporated in the control coordination formulation, using the property that eigenvectors associated with distinct modes are linearly independent. The robustness of the controllers is achieved very directly through extending the sets of equality constraints and inequality constraints in relation to selected eigenvalues and eigenvectors associated with the state matrices of power systems with loading conditions and/or network configurations different from that of the base case. On recognising that the fixed-parameter controllers, even when designed with optimal control coordination, have an inherent limitation which precludes optimal system damping for each and every possible system operating condition, the second part of ii the research has a focus on adaptive control techniques and their applications to power system controllers. In this context, the thesis reports the development of a new design procedure for online control coordination which leads to adaptive PSSs and/or supplementary damping controllers (SDCs) of FACTS devices for enhancing the stability of the electromechanical modes in a multi-machine power system. The controller parameters are adaptive to the changes in system operating condition and/or configuration. Central to the design is the use of a neural network synthesised to give in its output layer the optimal controller parameters adaptive to system operating condition and configuration. A novel feature of the neural adaptive controller is that of representing the system configuration by a reduced nodal impedance matrix which is input to the neural network.
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You, Ruhua. "Controller design for PSS and FACTS devices to enhance damping of low-frequency power oscillations in power systems." Diss., Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/you/YouR0506.pdf.
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Hadjikypris, Melios. "Supervisory control scheme for FACTS and HVDC based damping of inter-area power oscillations in hybrid AC-DC power systems." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/supervisory-control-scheme-for-facts-and-hvdc-based-damping-of-interarea-power-oscillations-in-hybrid-acdc-power-systems(cc03b44a-97f9-44ec-839f-5dcbcf2801f1).html.
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Modern interconnected power systems are becoming highly complex and sophisticated, while increasing energy penetrations through congested inter-tie lines causing the operating point approaching stability margins. This as a result, exposes the overall system to potential low frequency power oscillation phenomena following disturbances. This in turn can lead to cascading events and blackouts. Recent approaches to counteract this phenomenon are based on utilization of wide area monitoring systems (WAMS) and power electronics based devices, such as flexible AC transmission systems (FACTS) and HVDC links for advanced power oscillation damping provision. The rise of hybrid AC-DC power systems is therefore sought as a viable solution in overcoming this challenge and securing wide-area stability. If multiple FACTS devices and HVDC links are integrated in a scheme with no supervising control actions considered amongst them, the overall system response might not be optimal. Each device might attempt to individually damp power oscillations ignoring the control status of the rest. This introduces an increasing chance of destabilizing interactions taking place between them, leading to under-utilized performance, increased costs and system wide-area stability deterioration. This research investigates the development of a novel supervisory control scheme that optimally coordinates a parallel operation of multiple FACTS devices and an HVDC link distributed across a power system. The control system is based on Linear Quadratic Gaussian (LQG) modern optimal control theory. The proposed new control scheme provides coordinating control signals to WAMS based FACTS devices and HVDC link, to optimally and coherently counteract inter-area modes of low frequency power oscillations inherent in the system. The thesis makes a thorough review of the existing and well-established improved stability practises a power system benefits from through the implementation of a single FACTS device or HVDC link, and compares the case –and hence raises the issue–when all active components are integrated simultaneously and uncoordinatedly. System identification approaches are also in the core of this research, serving as means of reaching a linear state space model representative of the non-linear power system, which is a pre-requisite for LQG control design methodology.
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Johansson, Nicklas. "Aspects on Dynamic Power Flow Controllers and Related Devices for Increased Flexibility in Electric Power Systems." Doctoral thesis, KTH, Elektriska maskiner och effektelektronik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37823.
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This thesis studies different aspects of Flexible AC Transmission System (FACTS) devices which are used to improve the power transfer capability and increase the controllability in electric power systems. In the thesis, different aspects on the usage and control of Dynamic Power Flow Controllers (DPFC) and related FACTS devices are studied. The DPFC is a combination of a Phase Shifting Transformer (PST) and a Thyristor Switched Series Capacitor (TSSC)/Thyristor Switched Series Reactor (TSSR). The thesis proposes and studies a new method, the Ideal Phase-Shifter (IPS) method, for selection and rating of Power Flow Controllers (PFC) in a power grid. The IPS method, which is based on steady-state calculations, is proposed as a first step in the design process for a PFC. The method uses the Power controller plane, introduced by Brochu et al in 1999. The IPS method extends the usage of decoupling methods in the Power controller plane to a power system of arbitrary size. The IPS method was in the thesis used to compare the ratings of different PFC:s required to improve the power transfer capability in two test systems. The studied devices were here the PST, the TSSC/TSSR and the DPFC. The thesis treats control of ideal Controlled Series Capacitors (CSC), TCSC, TSSC/TSSR, and DPFC. The goals of the FACTS controllers which are developed are Power Oscillation Damping (POD), fast power flow control, and transient stability improvement in the power system. New adaptive control strategies for POD and power flow control are proposed and studied in different models of power systems by time-domain simulations. A strategy for transient stability improvement is also proposed and studied. Additionally, different methods for study of Subsynchronous Resonance (SSR), which is associated with series compensation in power systems, are investigated. Here, four of the most common methods for frequency scanning to determine the electrical damping of subsynchronous oscillations in a power grid are studied. The study reveals significant differences of the electrical damping estimates of the studied standard methods when applied to a four-machine test system.<br>QC 20110819
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Johansson, Nicklas. "Control of Dynamically Assisted Phase-shifting Transformers." Licentiate thesis, Stockholm : Elektrotekniska system, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4653.
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Martins, Luís Fabiano Barone [UNESP]. "Aplicação de algoritmos bio-inspirados na parametrização dos controladores suplementares de amortecimento e dispositivo FACTS UPFC." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151487.
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Previous issue date: 2017-08-22<br>Neste trabalho são apresentados quatro métodos de otimização bio-inspirados, Colônia de Abelhas Artificiais, Otimização por Enxame de Partículas, Algoritmo dos Vagalumes e um híbrido aqui denominado por Bee – PSO, que combina particularidades dos outros três. Estes métodos são utilizados no ajuste coordenado dos parâmetros dos controladores Proporcional-Integral e Suplementares de Amortecimento (Estabilizadores de Sistemas de Potência e o conjunto Unified Power Flow Controller – Power Oscillation Damping). O objetivo é inserir amortecimento adicional aos modos oscilatórios de baixa frequência e, consequentemente, garantir a estabilidade do sistema elétrico frente a pequenas perturbações. São considerados três cenários que englobam duas configurações de instalação dos controladores suplementares e duas condições de carregamento, uma fixa e outra variável. Uma formulação por injeções de corrente do dispositivo Unified Power Flow Controller é sugerida e incorporada ao Modelo de Sensibilidade de Corrente, utilizado para representar o sistema elétrico de potência. Análises estática e dinâmica foram realizadas nos sistemas teste Simétrico de Duas Áreas e New England para validar o modelo de injeções de corrente proposto para o Unified Power Flow Controller e determinar qual dos algoritmos apresentados é o mais eficiente no ajuste coordenado dos parâmetros dos controladores. Dos resultados obtidos foi possível concluir que a versão híbrida proposta neste trabalho possui desempenho superior na maioria dos cenários analisados, fornecendo soluções com amortecimento suficiente, mesmo quando pequenas variações no carregamento do sistema são consideradas.<br>In this work four bio-inspired optimization methods, Artificial Bee Colony, Particle Swarm Optimization, Firefly Algorithm, and a hybrid called Bee – PSO, which combines the characteristics of the other three are presented. These methods are used in the coordinated adjustment of the parameters of Proportional-Integral and Supplementary Damping Controllers (Power System Stabilizers and the Unified Power Flow Controller - Power Oscillation Damping). The goal is to insert additional damping into the low-frequency oscillatory modes and thus ensure the stability of the electrical system against minor disturbances. Three scenarios are considered that include two installation configurations of the supplementary controllers and two charging conditions, one fixed and one variable. A current injection formulation of the Unified Power Flow Controller is suggested and incorporated into the Current Sensitivity Model used to represent the electric power system. Static and dynamic analyzes were performed in the Two-Zone Symmetric and New England test systems to validate the proposed current injection model for the Unified Power Flow Controller and to determine which of the presented algorithms is the most efficient in the coordinated adjustment of the parameters of the controllers. From the results obtained it was possible to conclude that the hybrid version proposed in this work has superior performance in most scenarios analyzed, providing solutions with sufficient damping, even when small variations in system loading are considered.
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Martins, Luís Fabiano Barone. "Aplicação de algoritmos bio-inspirados na parametrização dos controladores suplementares de amortecimento e dispositivo FACTS UPFC /." Ilha Solteira, 2017. http://hdl.handle.net/11449/151487.
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Orientador: Percival Bueno de Araujo<br>Resumo: Neste trabalho são apresentados quatro métodos de otimização bio-inspirados, Colônia de Abelhas Artificiais, Otimização por Enxame de Partículas, Algoritmo dos Vagalumes e um híbrido aqui denominado por Bee – PSO, que combina particularidades dos outros três. Estes métodos são utilizados no ajuste coordenado dos parâmetros dos controladores Proporcional-Integral e Suplementares de Amortecimento (Estabilizadores de Sistemas de Potência e o conjunto Unified Power Flow Controller – Power Oscillation Damping). O objetivo é inserir amortecimento adicional aos modos oscilatórios de baixa frequência e, consequentemente, garantir a estabilidade do sistema elétrico frente a pequenas perturbações. São considerados três cenários que englobam duas configurações de instalação dos controladores suplementares e duas condições de carregamento, uma fixa e outra variável. Uma formulação por injeções de corrente do dispositivo Unified Power Flow Controller é sugerida e incorporada ao Modelo de Sensibilidade de Corrente, utilizado para representar o sistema elétrico de potência. Análises estática e dinâmica foram realizadas nos sistemas teste Simétrico de Duas Áreas e New England para validar o modelo de injeções de corrente proposto para o Unified Power Flow Controller e determinar qual dos algoritmos apresentados é o mais eficiente no ajuste coordenado dos parâmetros dos controladores. Dos resultados obtidos foi possível concluir que a versão híbrida proposta neste trabalho possui desempenho s... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: In this work four bio-inspired optimization methods, Artificial Bee Colony, Particle Swarm Optimization, Firefly Algorithm, and a hybrid called Bee – PSO, which combines the characteristics of the other three are presented. These methods are used in the coordinated adjustment of the parameters of Proportional-Integral and Supplementary Damping Controllers (Power System Stabilizers and the Unified Power Flow Controller - Power Oscillation Damping). The goal is to insert additional damping into the low-frequency oscillatory modes and thus ensure the stability of the electrical system against minor disturbances. Three scenarios are considered that include two installation configurations of the supplementary controllers and two charging conditions, one fixed and one variable. A current injection formulation of the Unified Power Flow Controller is suggested and incorporated into the Current Sensitivity Model used to represent the electric power system. Static and dynamic analyzes were performed in the Two-Zone Symmetric and New England test systems to validate the proposed current injection model for the Unified Power Flow Controller and to determine which of the presented algorithms is the most efficient in the coordinated adjustment of the parameters of the controllers. From the results obtained it was possible to conclude that the hybrid version proposed in this work has superior performance in most scenarios analyzed, providing solutions with sufficient damping, even when smal... (Complete abstract click electronic access below)<br>Doutor
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Maherani, Mahshid [Verfasser], and Gerhard [Akademischer Betreuer] Krost. "Design of Fixed Order Nonsmooth Robust H∞ MIMO Wide Area Controller for Damping of Inter Area Oscillations in Power Grids / Mahshid Maherani ; Betreuer: Gerhard Krost." Duisburg, 2019. http://d-nb.info/1200352807/34.
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Athanasius, Germane Information Technology & Electrical Engineering Australian Defence Force Academy UNSW. "Robust decentralised output feedback control of interconnected grid system." Awarded by:University of New South Wales - Australian Defence Force Academy, 2008. http://handle.unsw.edu.au/1959.4/39591.
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The novel contribution of the thesis is the design and implementation of decentralised output feedback power system controllers for power oscillation damping (POD) over the entire operating regime of the power system. The POD controllers are designed for the linearised models of the nonlinear power system dynamics. The linearised models are combined and treated as parameter varying switched systems. The thesis contains novel results for the controller design, bumpless switching and stability analysis of such switched systems. Use of switched controllers against the present trend of having single controller helps to reduce the conservatism and to increase the uncertainty handling capability of the power system controller design. Minimax-LQG control design method is used for the controller design. Minimax-LQG control combines the advantages of both LQG and H control methods with respect to robustness and the inclusion of uncertainty and noise in the controller design. Also, minimax-LQG control allows the use of multiple integral quadratic constraints to bound the different types of uncertainties in the power system application. During switching between controllers, switching stability of the system is guaranteed by constraining the minimum time between two consecutive switchings. An expression is developed to compute the minimum time required between switchings including the effect of jumps in the states. Bumpless switching scheme is used to minimise the switching transients which occur when the controllers are switched. Another contribution of the thesis is to include the effect of on load tap changing transformers in the power system controller design. A simplified power system model linking generator and tap changing transformer dynamics is developed for this purpose and included in the controller design. The performance of the proposed linear controllers are validated by nonlinear computer simulations and through real time digital simulations. The designed controllers improve power system damping and provide uniform performance over the entire operating regime of the generator.
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Fortes, Elenilson de Vargas [UNESP]. "Aplicação do algoritmo genético de Chu-Beasley especializado no ajuste dos parâmetros dos controladores suplementares e dispositivo FACTS IPFC." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144513.
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Previous issue date: 2016-10-21<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Este trabalho apresenta o Algoritmo Genético de Chu-Beasley Especializado para realizar o ajuste coordenado dos parâmetros de controladores Proporcional-Integral e suplementares de amortecimento (Estabilizadores de Sistemas de Potência e Interline Power Flow Controller - Power Oscillation Damping) em sistemas elétricos de potência multimáquinas. O objetivo principal deste trabalho é inserir amortecimento adicional às oscilações eletromecânicas de baixa frequência classificadas como local e interárea. Para representar o sistema, é utilizado o Modelo de Sensibilidade de Corrente. Desse modo, todos os seus dispositivos e componentes foram modelados por injeção de corrente e, portanto, um novo modelo de injeção de corrente para o Interline Power Flow Controller é apresentado. Três sistemas teste foram utilizados nas simulações realizadas neste trabalho, sendo: Simétrico de Duas Áreas, New England e o Sul Brasileiro Reduzido. O desempenho da metodologia proposta (Algoritmo Genético de Chu-Beasley Especializado), no que concerne ao ajuste dos parâmetros dos controladores, foi comparado a outros dois algoritmos bastantes difundidos na literatura: Particle Swarm Optimization e o Algoritmo Genético com Elitismo. Os resultados demonstraram que o algoritmo Genético de Chu-Beasley Especializado foi mais eficiente que as demais técnicas apresentadas, obtendo soluções robustas quando variações de cargas foram consideradas, sendo, portanto, credenciado como ferramenta no estudo da análise da estabilidade a pequenas perturbações.<br>CNPq: 141084/2016-2
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Fortes, Elenilson de Vargas. "Aplicação do algoritmo genético de Chu-Beasley especializado no ajuste dos parâmetros dos controladores suplementares e dispositivo FACTS IPFC /." Ilha Solteira, 2016. http://hdl.handle.net/11449/144513.
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Orientador: Percival Bueno de Araujo<br>Resumo: Este trabalho apresenta o Algoritmo Genético de Chu-Beasley Especializado para realizar o ajuste coordenado dos parâmetros de controladores Proporcional-Integral e suplementares de amortecimento (Estabilizadores de Sistemas de Potência e Interline Power Flow Controller - Power Oscillation Damping) em sistemas elétricos de potência multimáquinas. O objetivo principal deste trabalho é inserir amortecimento adicional às oscilações eletromecânicas de baixa frequência classificadas como local e interárea. Para representar o sistema, é utilizado o Modelo de Sensibilidade de Corrente. Desse modo, todos os seus dispositivos e componentes foram modelados por injeção de corrente e, portanto, um novo modelo de injeção de corrente para o Interline Power Flow Controller é apresentado. Três sistemas teste foram utilizados nas simulações realizadas neste trabalho, sendo: Simétrico de Duas Áreas, New England e o Sul Brasileiro Reduzido. O desempenho da metodologia proposta (Algoritmo Genético de Chu-Beasley Especializado), no que concerne ao ajuste dos parâmetros dos controladores, foi comparado a outros dois algoritmos bastantes difundidos na literatura: Particle Swarm Optimization e o Algoritmo Genético com Elitismo. Os resultados demonstraram que o algoritmo Genético de Chu-Beasley Especializado foi mais eficiente que as demais técnicas apresentadas, obtendo soluções robustas quando variações de cargas foram consideradas, sendo, portanto, credenciado como ferramenta no estudo da análise d... (Resumo completo, clicar acesso eletrônico abaixo)<br>Doutor
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Miotto, Ednei Luiz. "Aplicação do algoritmo bioinspirado Novel Bat Algorithm na parametrização dos controladores suplementares de amortecimento e dispositivo FACTS GUPFC." Ilha Solteira, 2018. http://hdl.handle.net/11449/157493.
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Orientador: Percival Bueno de Araujo<br>Resumo: Este trabalho apresenta o Novel Bat Algorithm com uma nova técnica para realizar o ajuste coordenado dos parâmetros de controladores suplementares de amortecimento (Estabilizadores de Sistemas de Potência e do conjunto Generalized Unified Power Flow Controller – Power Oscillation Damping) em sistemas elétricos de potência multimáquinas. O objetivo principal é inserir amortecimento adicional aos modos oscilatórios de baixa frequência e, consequentemente, garantir a estabilidade do sistema elétrico frente a pequenas perturbações. Para representar o sistema elétrico de potência será utilizado o Modelo de Sensibilidade de Potência. Desse modo, todos os seus dispositivos e componentes foram modelados por injeções de potência. Análises estáticas e dinâmicas foram realizadas em dois sistemas teste, sendo: o Sistema Simétrico de Duas Áreas e o Sistema New England. A eficiência do dispositivo FACTS Generalized Unified Power Flow Controller atuando em conjunto com uma estrutura de controle baseada em controladores Proporcional – Integral foi criteriosamente avaliada para o controle de fluxos de potências ativa e reativa, para a melhoria do perfil de tensão do sistema elétrico e na redução das perdas no sistema de transmissão. O desempenho do Novel Bat Algorithm, no que concerne ao ajuste dos parâmetros dos controladores, foi comparado a outros quatro algoritmos bio-inspirados bastante difundidos na literatura: Particle Swarm Optimization, Bacterial Foragim Optimization, Bat Algorithm e... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: This work presents the Novel Bat Algorithm as a new technique for the to perform the coordinated tuning of the parameters of the supplementary damping controllers (Power Systems Stabilizers and Generalized Unified Power Flow Controller - Power Oscillation Damping) in multi-machine electric power systems. The main objective is to insert damping to low-frequency oscillations and thus ensure the stability of the electrical system against minor disturbances. The Power Sensitivity Model is used to represent the system. Thus, all devices and their components are modeled by power injection. Static and dynamic analyzes were performed in the two systems: the two-areas symmetric, and the New England. The performance of the proposed methodology (Novel Bat Algorithm), for tuning of the parameters of the controllers was compared to four other algorithms, presented in the literature: The Particle Swarm Optimization method, Bacterial Foraging Optimization method, Bat Algorithm method and a Genetic Algorithm with elitism. The results demonstrated that the Novel Bat Algorithm was more effective than the other techniques presented, generating robust solutions when variations on the scenarios of loads were considered, and therefore accredited it as a tool in the analysis of the study of small-signal stability.<br>Doutor
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Banejad, Mahdi. "Identification of damping contribution from power system controllers." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15851/1/Mahdi_Banejad_Thesis.pdf.
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With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.
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Banejad, Mahdi. "Identification of Damping Contribution from Power System Controllers." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15851/.
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With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.
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Cai, L. Erlich J. "Fuzzy Coordination of FACTS Controllers for Damping Power System Oscillations, MEPS Conference 2002." Gerhard-Mercator-Universitaet Duisburg, 2003. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-04142003-130952/.
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This paper concerns the optimization and coordination of the conventional FACTS (Flexible AC Transmission Systems) damping controllers in multi-machine power system. Firstly, the parameters ofFACTS controller are optimized. Then, a hybrid fuzzy logic controller for the coordination of FACTS controllers is presented. This coordination method is well suitable to series connected FACTS devices like UPFC, TCSC etc. in damping multi-modal oscillations in multi-machine power systems. Digital simulations of a multi-machine power system subjected to a wide variety of disturbances and different structures validate the efficiency of the new approach.
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Arif, Jawad. "Nonlinear self-tuning control for power oscillation damping." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7035.
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Power systems exhibit nonlinear behavior especially during disturbances, necessitating the application of appropriate nonlinear control techniques. Lack of availability of accurate and updated models for the whole power system adds to the challenge. Conventional damping control design approaches consider a single operating condition of the system, which are obviously simple but tend to lack performance robustness. Objective of this research work is to design a measurement based self-tuning controller, which does not rely on accurate models and deals with nonlinearities in system response. Designed controller is required to ensure settling of inter-area oscillations within 10−12s, following disturbance such as a line outage. The neural network (NN) model is illustrated for the representation of nonlinear power systems. An optimization based algorithm, Levenberg-Marquardt (LM), for online estimation of power system dynamic behavior is proposed in batch mode to improve the model estimation. Careful study shows that the LM algorithm yields better closed loop performance, compared to conventional recursive least square (RLS) approach with the pole-shifting controller (PSC) in linear framework. Exploiting the capability of LM, a special form of neural network compatible with feedback linearization technique, is applied. Validation of the performance of proposed algorithm is done through the modeling and simulating heavy loading of transmission lines, when the nonlinearities are pronounced. Nonlinear NN model in the Feedback Linearization (FLNN) form gives better estimation than the autoregressive with an external input (ARX) form. The proposed identifier (FLNN with LM algorithm) is then tested on a 4−machine, 2−area power system in conjunction with the feedback linearization controller (FBLC) under varying operating conditions. This case study indicates that the developed closed loop strategy performs better than the linear NN with PSC. Extension of FLNN with FBLC structure in a multi-variable setup is also done. LM algorithm is successfully employed with the multi-input multi-output FLNN structure in a sliding window batch mode, and FBLC controller generates multiple control signals for FACTS. Case studies on a large scale 16−machine, 5−area power system are reported for different power flow scenarios, to prove the superiority of proposed schemes: both MIMO and MISO against a conventional model based controller. A coefficient vector for FBLC is derived, and utilized online at each time instant, to enhance the damping performance of controller, transforming into a time varying controller.
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Zhang, Pei. "Co-ordination and control of power system damping controllers to enhance small signal stability." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321949.
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Hansson, Johan. "Evaluation of Power Oscillation Damping in the Nordic Grid Using HVDC." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292745.
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With a rapid transition towards renewable energy sources and increasing demand for electricity, we are facing major changes in the electricity grid. With increased congestion and reduction of inertia the grid is becoming more sensitive to rotor angle stability issues, such as the stability of interarea modes or power oscillation damping (POD). This thesis shows that the use of local measurements for POD improvement could lead to reduced transient rotor angle stability. Depending on fault location it is shown that reduction of the first swing is not always feasible, and depending on the controller the first swing could be amplified and in the worst case lead to a power blackout due to the tripping of generators and transmission lines. The reason for the behavior is, among other things, rooted in the fundamental limitations of using local measurements, where the estimate of the inter-area mode detects the wrong signs of the disturbance. Nonlinear simulations are performed in the nordic32 bus Simulink model in order to validate the results.<br>Med en snabb övergång till förnybara energikällor och ökad efterfrågan på el står vi inför stora förändringar i elnätet. Med ökad belastning och minskad rörelsemängd blir nätet mer känsligt för problem relaterade till rotorvinkelstabilitet, så som stabiliteten av interareapendlingar eller kraftoscillationsdämpning (POD). Denna avhandling visar att användningen av lokal mätning för POD-förbättring kan leda till minskad transient rotorvinkelstabilitet. Beroende på var felet inträffar visas det att dämpning av den första svängningen inte alltid är möjlig, och beroende på regulatorndesign kan den första svängningen förstärkas och i värsta fall leda till en strömavbrott på grund av brotkopplade generatorer eller transmissionsledningar. Detta fenomen är bland annat sprunget ur de fundamentala begränsningarna i användnignen av lokal mätning, där estimeringen av interareapendlingen initialt estimerar fel tecken på störningen. Icke- linjära simuleringar utförs i nordic32 Simulink-modellen för att validera resultaten.
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Cordero, Bautista Luis Gustavo. "Aplicação do algoritmo genético adaptativo com hipermutação no ajuste dos parâmetros dos controladores suplementares e dispositivo FACTS IPFC /." Ilha Solteira, 2019. http://hdl.handle.net/11449/182292.
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Orientador: Percival Bueno de Araujo<br>Resumo: As perturbações ou variações de carga produzem oscilações eletromecânicas que devem ser amortecidas o mais rápido possível para garantir confiabilidade e estabilidade da rede. Neste trabalho apresenta-se uma análise do dispositivo FACTS Interline Power Flow Controller (IPFC) e o controlador Proporcional Integral (PI) no gerenciamento dos fluxos de potência e a influência dos Estabilizadores do Sistema de Potência (ESP) e do IPFC Power Oscillation Damping (POD) sobre a estabilidade do sistema elétrico de potência. Neste trabalho enfoca-se nos estudos de estabilidade a pequenas perturbações usando um Algoritmo Genético Adaptativo com Hiper-mutação (AGAH) para ajustar os parâmetros dos controladores suplementares de amortecimento, o Estabilizador de sistema de potência (ESPs) e o Power Oscillation Damping (POD) em forma coordenada. O AGAH tem como objetivo encontrar os parâmetros ótimos do controlador para melhorar o amortecimento fraco das oscilações de baixa frequência locais e inter-área. Neste trabalho representa-se o sistema de elétrico de potência com a inclusão do dispositivo Interline Power Flow Controller com o modelo de sensibilidade de corrente (MSC). Considera-se como sistema teste o sistema Simétrico de Duas Áreas e o sistema New England como o intuito de avaliar o algoritmo proposto. As simulações são feitas no ambiente do MatLab. Por fim, apresenta-se a comparação do algoritmo genético com o desempenho do algoritmo proposto.<br>Abstract: Small-magnitude disturbances happen to produce electro-mechanical oscillations which should be damped as quickly as possible to ensure reliability and stability of the network. This work presents an analysis of Interline Power Flow Controller (IPFC) FACTS device and PI controller to control and manage power flow and also how Power System Stabilizers and IPFC Power Oscillations Damping (POD) controller influence over an electric power system stability. This work focuses on small-signal stability studies using an Adaptive Genetic Algorithm with Hyper-mutation (AGAH) in order to tune controller parameters in a coordinated way ensuring proper damping. AGAH aims to find optimal controller parameters to enhance the poor damping of local and inter-area low frequency oscillations. This works represents the electric power system and Interline Power Flow Controller device by a current sensitivity model (CSM). This paper considers two areas 14 bus symmetrical power system and New England power system in order to assess proposed algorithm. Coding and Simulations take place in MatLab platform. AGAH and GA get compared by time convergence and performance. This paper shows AGAH is an interesting optimization technique which outweighs GA.<br>Mestre
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Björk, Joakim. "Performance Quantification of Interarea Oscillation Damping Using HVDC." Licentiate thesis, KTH, Reglerteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-245223.
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With the transition towards renewable energy, and the deregulation of the electricity market, generation patterns and grid topology are changing. These changes increase the need for transfer capacity. One limiting factor, which sometimes leads to underutilization of the transmission grid, is interarea oscillations. These system-wide modes involve groups of generators oscillating relative to each other and are sometimes hard to control due to their scale and complexity. In this thesis we investigate how high-voltage direct current (HVDC) transmission can be used to attenuate interarea oscillations. The thesis has two main contributions. In the first contribution we show how the stability of two asynchronous grids can be improved by modulating the active power of a single interconnecting HVDC link. One concern with modulating HVDC active power is that the interaction between interarea modes of the two grids may have a negative impact on system stability. By studying the controllability Gramian, we show that it is always possible to improve the damping in both grids as long as the frequencies of their interarea modes are not too close. For simplified models, it is explicitly shown how the controllability, and therefore the achievable damping improvements, deteriorates as the frequency difference becomes small. The second contribution of the thesis is to show how coordinated control of two (or more) links can be used to avoid interaction between troublesome interarea modes. We investigate the performance of some multivariable control designs. In particular we look at input usage as well as robustness to measurement, communication, and actuator failures. Suitable controllers are thereby characterized.<br>Övergången till förnybar energi och avregleringen av elmarknaden leder till förändrade produktions-och överföringsmönster. Dessa förändringar medför behov av en ökad överföringskapacitet. En begränsande faktor, som kan leda till ett underutnyttjande av stamnätet, är interareapendlingar. Dessa systemövergripande pendlingar involverar grupper av generatorer som svänger i förhållande till varandra. Interareapendlingar är ibland svåra att styra på grund av deras skala och komplexitet. I denna avhandling undersöker vi hur förbindelser med högspänd likström, engleska high-voltage direct current (HVDC), kan användas för att dämpa interareapendlingar. Avhandlingen har två huvudbidrag. I det första bidraget visar vi hur stabiliteten hos två olika synkrona nät kan förbättras genom att modulera den aktiva effekten hos en enda HVDC-länk. Ett bekymmer med aktiv effektmodulering är att växelverkan mellan interareapendlingar hos de två näten kan ha en negativ inverkan på systemets stabilitet. Genom att studera styrbarhetsgramianen visar vi att det alltid är möjligt att förbättra dämpningen i båda näten så länge som frekvenserna hos deras interareapendlingar inte ligger för nära varandra. För förenklade modeller visas det uttryckligen hur styrbarheten och därmed de möjliga dämpningsförbättringarna, försämras då frekvensskillnaden blir liten. Avhandlings andra bidrag visar hur koordinerad styrning av två (eller fler) länkar kan användas för att undvika växelverkan mellan besvärliga interareapendlingar. Vi undersöker prestandan hos olika typer av flervariabla regulatorer. I synnerhet undersökers styrsignalsanvändning samt robusthet mot mät-, kommunikations- och aktuatorfel. Därigenom karakteriseras lämpliga regulatortyper.<br><p>QC 20190308</p>
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Snyder, Aaron Francis. "Inter-Area Oscillation Damping with Power System Stabilizers and Synchronized Phasor Measurements." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/35434.
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Low frequency oscillations are detrimental to the goals of maximum power transfer and optimal power system security. A contemporary solution to this problem is the addition of power system stabilizers to the automatic voltage regulators on the generators in the power system. The damping provided by this additional stabilizer provides the means to reduce the inhibiting effects of the oscillations.
This thesis is an investigation of the use of synchronized phasor measurements as input signals for power system stabilizers installed on the generators of a two-area, 4-machine test power system. A remote measurement feedback controller has been designed and placed in the test power system. Synchronized phasor measurements from optimally sited measurement units were shown to improve the damping of low-frequency inter-area oscillations present in the test system when the proposed controller was included in the generator feedback control loop. The benefit of the damping of these oscillations was evident through the ability to increase the tie-line power flowing in the test system once the proposed control scheme was implemented. Time-domain simulations were used to verify the robustness of the proposed control during severe events, such as a short- circuit or sudden large variations of load.<br>Master of Science
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Björk, Erik. "Load Characteristic Influence on Power Oscillation Damping : Case Study on HVDC-interconnected AC-Grids." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235199.
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The increasing share of renewables in the electric grid may have a negative impact on the systemstability to which conventional control methods are insucient. The report focuses on the stabilityof low frequency inter-area modes. Along the development of renewables, power electronics aremore frequently used between the actual load and the grid. Hence the characteristics of the loadsis undergoing a change as well. This report investigates how dierent load characteristics inuencethe damping in the grids. The investigation is performed by a simulation experiment where a modelconsisting of two AC-grids interconnected via an HVDC-link is implemented in two simulation softwareprograms, PSCAD and Simulink. The HVDC-link has an implemented active power oscillationdamping control to improve the damping of the overall system. The report also review which softwarethat is most suitable for the given investigation. It is shown that active power loads contributesto the damping best if they are modelled as constant impedance loads and less for constant powerloads. Reactive loads with inductive behaviour contributes to the damping best if they are modelledas constant power loads and contributes least if they are constant impedance loads. The evidencesuggest that the damping provided by the loads is uncorrelated with the damping provided by theHVDC-link. The simulation software that suited the author's preference best was Simulink. Theseresults contribute to the understanding of how loads inuence the system damping and can be usedin future studies, where it is interesting to know if the load damping is over or underestimated.<br>ökande andelen av förnyelsebara energikällor som integreras till elsystemet kan ha en negativpåverkan på elsystemets stabilitet vilket gör att konventionella metoder för att stabilisera system kan visa sig vara otillräckliga. Parallellt med utvecklingen av förnyelsebara energikällor ökar andelen av kraftelektronik som kopplas mellan lasten och elnätet. Den adderade kraftelektroniken till lasten förändrar följaktligen karaktären av lasterna. Rapporten undersöker olika lastkaraktärers inverkan på dämpningen av lågfrekventa svängningsmoder i elsystemet. Studien utförs genom ett simuleringsexperiment där en modell bestående av två AC-nät som är sammankopplade med en HVDC-länk implementeras i två olika simuleringsprogram, PSCAD och Simulink. HVDC-länken har en regulator implementerad för att dämpa de aktiva effektoscillationerna i systemet. Rapporten undersöker även vilket simulationsprogram som är mest lämpad för den utförda studien. Resultaten visar att laster som konsumerar aktiv effekt gav bäst dämpning när de var modellerade som konstanta impedanslaster och de gav sämst dämpning när de var konstanta effektlaster. Laster som konsumerade reaktiv effekt, induktiva laster, gav bäst dämpning till systemet när de var modellerade som konstanta effekt laster och gav sämst dämpning när de var modellerade som konstanta impedans laster. Dessutom tyder resultaten på att dämpningen given från lasterna inte är korrelerade med dämningen från HVDClänken. Simuleringsprogrammet som enligt författarens preferenser var mest lämpad för studien var Simulink. Resultaten kan bidra till en ökad förståelse av lasters påverkan på elsystemets dämpning och kan användas i framtida studier, där det är av intresse att veta om lastens dämpning är över ellerunderskattad
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Zou, Xiaolan. "Frequency and Damping Characteristics of Generators in Power Systems." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/81937.
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A power system stability is essential for maintaining the power system oscillation frequency within a small and acceptable interval around its nominal frequency. Hence, it is necessary to study and control the frequency for stable operation of a power system by knowing the characteristics within a power system. One approach is to understand the effectiveness of frequency and damping characteristics of generators in power systems. Hence, the simulation analysis of IEEE 118-bus power system is used for this study. The analysis includes theoretical analysis with a mathematical approach and simulation studies of swing equation to determine the characteristics of damped single-machine infinite bus, which is represented as a generator connects to a large network system with a small signal disturbance by line losses. Additionally, mathematical derivation of Prony analysis is presented in order to estimate the frequency and damping ratio of the simulation results. In the end, the results demonstrate that the frequency and damping characteristics of generators are highly dependent on the system inertia constant. Therefore, the higher inertia constant is a critical factor to ensure the system is more stable.<br>Master of Science
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Almutairi, Abdulaziz. "Enhancement of power system stability using wide area measurement system based damping controller." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/enhancement-of-power-system-stability-using-wide-area-measurement-system-based-damping-controller(7d98d164-8051-4662-ad18-374620d28a00).html.
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Contemporary power networks are gradually expanding incorporating new sources of electrical energy and power electronic based devices. The major stability issue in large interconnected power systems is the lightly damped interarea oscillations. In the light of growth of their incidents there are increased concerns about the effectiveness of current control devices and control systems in maintaining power system stability. This thesis presents a Wide Area Measurement System (WAMS) based control scheme to enhance power system stability. The control scheme has a hierarchical (two-level) structure comprising a Supplementary Wide-Area Controller (SWAC) built on top of existing Power System Stabilisers (PSSs). The SWAC's focus is on stabilising the critical interarea oscillations in the system while leaving local modes to be controlled entirely by local PSSs. Both control systems in the two levels work together to maintain system stability. The scheme relies on synchronised measurements supplied by Phasor Measurement Units (PMUs) through the WAMS and the only cost requirement is for the communication infrastructure which is already available, or it will be in the near future. A novel linear quadratic Gaussian (LQG) control design approach which targets the interarea modes directly is introduced in this thesis. Its features are demonstrated through a comparison with the conventional method commonly used in power system damping applications. The modal LQG approach offers simplicity and flexibility when targeting multiple interarea modes without affecting local modes and local controllers, thus making it highly suitable to hierarchical WAMS based control schemes. Applicability of the approach to large power systems is demonstrated using different scenarios of model order reduction. The design approach incorporates time delays experienced in the transmission of the SWAC's input/output signals. Issues regarding values of time delays and required level of detail in modelling time delays are thoroughly discussed. Three methods for selection of input/output signals for WAMS based damping controllers are presented and reviewed. The first method uses modal observability/controllability factors. The second method is based on the Sequential Orthogonalisation (SO) algorithm, a tool for the optimal placement of measurement devices. Its application is extended and generalised in this thesis to handle the problem of input/output signal selection. The third method combines clustering techniques and modal factor analysis. The clustering method uses advanced Principal Component Analysis (PCA) where its draw backs and limitations, in the context of power system dynamics' applications, are overcome. The methods for signal selection are compared using both small signal and transient stability analysis to determine the best optimal set of signals. Enhancement of power system stability is demonstrated by applying the proposed WAMS based control scheme on the New England test system. The multi-input multi-output (MIMO) WAMS based damping controller uses a reduced set of input/output signals and is designed using the modal LQG approach. Effectiveness of the control scheme is comprehensively assessed using both small signal and transient stability analysis for different case studies including small and large disturbances, changes in network topology and operating condition, variations in time delays, and failure of communication links.
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Hasanović, Amer. "A simulation and analysis toolbox for power systems and genetic algorithm based damping controller design." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2173.
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Thesis (M.S.)--West Virginia University, 2001.<br>Title from document title page. Document formatted into pages; contains viii, 73 p. : ill. Includes abstract. Includes bibliographical references (p. 71-73).
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Preece, Robin. "A probabilistic approach to improving the stability of meshed power networks with embedded HVDC lines." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/a-probabilistic-approach-to-improving-the-stability-of-meshed-power-networks-with-embedded-hvdc-lines(b7e4843f-52b4-4ccf-88ad-48f9195b7270).html.
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This thesis investigates the effects of High Voltage Direct Current (HVDC) lines andmulti-terminal grids on power system small-disturbance stability in the presence ofoperational uncertainties. The main outcome of this research is the comprehensiveprobabilistic assessment of the stability improvements that can be achieved through theuse of supplementary damping control applied to HVDC systems.Power systems are increasingly operated closer to stability boundaries in order toimprove their efficiency and economic value whilst a growing number of conventionalcontrolled power plants are being replaced by stochastic renewable generation sources.The resulting uncertainty in conditions can increase the risk of operational stabilityconcerns and should be thoroughly evaluated. There is also a growing necessity toexplore the potential improvements and challenges created by the introduction of newequipment, such as HVDC systems. In recent years, HVDC systems have become moreeconomically competitive and increasingly flexible, resulting in a proliferation ofprojects. Although primarily installed for power transmission purposes, their flexibilityand controllability can provide further benefits, such as the damping of persistentoscillations in the interconnected networks.This work contributes to a number of areas of power systems research, specificallysurrounding the effects of HVDC systems on the small-disturbance stability oftransmission networks. The application and comprehensive assessment of a Wide AreaMeasurement System (WAMS) based damping controller with various HVDC systemsis completed. The studies performed on a variety of HVDC technology types andconfigurations – as well as differing AC test networks – demonstrate the potential forHVDC-based Power Oscillation Damping (POD). These studies include examinationsof previously unexplored topics such as the effects of available modulation capacity andthe use of voltage source converter multi-terminal HVDC grids for POD. Followingthese investigations, a methodology to probabilistically test the robustness of HVDC based damping controllers is developed. This methodology makes use of classificationtechniques to identify possible mitigation options for power system operators whenperformance is sub-optimal. To reduce the high computational burden associated withthis methodology, the Probabilistic Collocation Method (PCM) is developed in order toefficiently identify the statistical distributions of critical system modes in the presenceof uncertainties. Methods of uncertain parameter reduction based on eigenvaluesensitivity are developed and demonstrated to ensure accurate results when the PCM isused with large test systems. Finally, the concepts and techniques introduced within thethesis are combined to probabilistically design a WAMS-based POD controller morerobust to operational uncertainties. The use of the PCM during the probabilistic designresults in rapid and robust synthesis of HVDC-based POD controllers.
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Arsoy, Aysen. "Electromagnetic Transient and Dynamic Modeling and Simulation of a StatCom-SMES Compensator in Power Systems." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/27225.
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Electromagnetic transient and dynamic modeling and simulation studies are presented for a StatCom-SMES compensator in power systems. The transient study aims to better understand the transient process and interaction between a high power/high voltage SMES coil and its power electronics interface, dc-dc chopper. The chopper is used to attach the SMES coil to a StatCom. Following the transient study, the integration of a StatCom with SMES was explored to demonstrate the effectiveness of the combined compensator in damping power oscillations. The transient simulation package PSCAD/EMTDC has been used to perform the integrated modeling and simulation studies.
A state of the art review of SMES technology was conducted. Its applications in power systems were discussed chronologically. The cost effective and feasible applications of this technology were identified. Incorporation of a SMES coil into an existing StatCom controller is one of the feasible applications, which can provide improved StatCom operation, and therefore much more flexible and controllable power system operation.
The SMES coil with the following unique design characteristics of 50MW (96 MW peak), 100 MJ, 24 kV interface has been used in this study. As a consequence of the high power/ high voltage interface, special care needs to be taken with overvoltages that can stress the insulation of the coil. This requires an investigation of transient overvoltages through a detailed modeling of SMES and its power electronics interface. The electrical model for the SMES coil was developed based on geometrical dimensions of the coil. The interaction between the SMES coil and its power electronics interface (dc-dc chopper for the integration to StatCom) was modeled and simulated to identify transient overvoltages. Transient suppression schemes were developed to reduce these overvoltages. Among these are MOV implementation, surge capacitors, different configurations of the dc-dc chopper.
The integration of the SMES coil to a StatCom controller was developed, and its dynamic behavior in damping oscillations following a three-phase fault was investigated through a number of simulation case studies. The results showed that the addition of energy storage to a StatCom controller can improve the StatCom-alone operation and can possibly reduce the MVA rating requirement for the StatCom operating alone. The effective location selection of a StatCom-SMES controller in a generic power system is also discussed.<br>Ph. D.
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Schoemacker, Florian, Felix Fischer, and Katharina Schmitz. "Damping strategies for energy efficient pressure controllers of variable displacement pumps." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71108.
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In hydraulic-mechanically controlled variable displacement pumps, the actual pump controller produces additional power losses. Due to the low damping coefficients of all pump controller’s components, hydraulic-mechanically pressure controlled pumps use to oscillate while adjusting the pressure level in the hydraulic system. In several state-of-the-art variable pump controllers, a damping orifice connects the control actuator’s displacement chamber with the reservoir. This bypass dampens the movement of the control actuator but also leads to bypass losses during steady-state operation of the pump. A new concept for damping via feedback loops avoiding bypass losses is presented in t his paper.
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Latorre, Hector F. "A Multichoice Control Strategy for a VSC-HVdc." Licentiate thesis, KTH, Elektriska energisystem, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4675.
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Utilization of power electronics based controllable systems (or devices) in transmission systems has opened new opportunities for the power industry to optimize utilization of the existing transmission systems, and at the same time to keep high system reliability and security. As a member of these controllable systems, Voltage Source Converters-based High Voltage direct current (VSC-HVdc) systems have the ability to rapidly control the transmitted active power, and also to independently exchange reactive power with transmissions systems. Therefore, VSC-HVdcs with a suitable control scheme can offer an alternative means to enhance transient stability, to improve power oscillations damping, and to provide voltage support. An interesting application of this system is the analysis of a power system when a VSC-HVdc is connected in parallel with ac transmission lines. This thesis presents the derivation of control strategies to damp power oscillations, to enhance the transient stability and to provide voltage support for a VSC-HVdc. The thesis also formulates a multichoice control strategy and its application when the VSC-HVdc is connected in a synchronous system. The control strategy for enhancing transient stability is based on the theory of Control Lyapunov Function. The control strategy for increasing the damping is based on Linear Analysis. A very effective well known way to increase damping in the system is modulating the active power through the HVdc. However, besides the control of active power, the thesis explores an alternative way to mitigate power oscillations by controlling the reactive power. This condition might be very useful when the dc link in the VSC-HVdc system is out of service, but the converter stations are in operating conditions. A simple model of VSC-HVdc is considered in order to test the control strategy. The model represents the VSC-HVdc as an element in the power system that provides adequate interaction with other systems elements. The model is intended for analysis of power flows and electromechanical transients. It is then sufficient to consider the power frequency components of voltages and currents represented by phasors that vary with time during transients. The model is valid for symmetrical conditions, i.e. positive sequence phasors are used for the representation of the electrical state.<br>QC 20101117
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Latorre, Hector. "A Multichoice Control Strategy for a VSC-HVdc." Licentiate thesis, Stockholm : Elektriska energisystem, Electric Power Systems, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4675.
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Ramos, Rodrigo Andrade. "Procedimento de projeto de controladores robustos para o amortecimento de oscilações eletromecânicas em sistemas de potência." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-11032003-074604/.
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Este trabalho propõe uma nova metodologia de projeto de controladores para o amortecimento de oscilações eletromecânicas de baixa freqüência em sistemas de potência. Considerando a necessidade de se aumentar a robustez dos estabilizadores clássicos frente a variações nas condições de operação, este estudo analisou uma série de requisitos práticos a serem atendidos pelos novos controladores de amortecimento e desenvolveu a metodologia proposta, de tal forma que os controladores projetados pudessem satisfazer a todos os requisitos analisados. Foram tratadas questões relativas à estrutura de controle (realimentação dinâmica descentralizada de saída), à robustez de estabilidade e desempenho (através da modelagem politópica e dos critérios de posicionamento regional de pólos) e da não atuação dos controladores em regime permanente (com a inclusão de filtros washout na modelagem). A principal vantagem desta metodologia proposta é a possibilidade de se garantir formalmente um desempenho robusto dos controladores, dentro de uma região pré-especificada de pontos de operação. Os resultados, obtidos através de simulações não lineares da resposta (para uma série de perturbações) dos sistemas escolhidos para teste, em diversas condições de operação, mostram que os controladores obtidos com a aplicação desta metodologia são capazes de manter seu desempenho frente às variações consideradas. Além disso, a obtenção de resultados satisfatórios com a aplicação desta metodologia a um sistema com 45 variáveis de estado indica boas perspectivas para a utilização conjunta da mesma com técnicas de redução do modelo de estados, para o projeto de controladores de amortecimento em sistemas reais de grande porte.<br>This research proposes a new methodology for the design of controllers to damp low frequency electromechanical oscillations in power systems. Considering the need to improve the robustness of the classical stabilizers, with respect to variations in the operating conditions, this study has analyzed a series of practical requirements to be met by the new damping controllers and developed the proposed methodology, so the designed controllers could satisfy all the analyzed equirements. Questions regarding the controller structure (decentralized dynamic output feedback), the robustness of stability and performance (through the polytopic modelling and the regional pole placement criteria) and the non influence of the controllers over the steady state behavior of the system (with the inclusion of washout filters in the model) were treated. The main advantage of the proposed methodology is the possibility to ensure, formally, the performance robustness of the controllers, within a previously specified region of operating points. The results, obtained through the eigenanalysis of the closed loop system and the nonlinear simulations of the system responses to a series of disturbances, in various operating conditions, show that the controllers provided by this new methodology are capable of maintaining their performance, despite the considered variations. Moreover, the satisfactory results obtained with the application of this methodology to a system with 45 state variables indicates good perspectives for the joint utilization of the methodology and model order reduction techniques, for the design of damping controllers for real-sized systems.
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Glickman, Mark. "Disturbance monitoring in distributed power systems." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16497/1/Mark_Glickman_Thesis.pdf.
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Power system generators are interconnected in a distributed network to allow sharing of power. If one of the generators cannot meet the power demand, spare power is diverted from neighbouring generators. However, this approach also allows for propagation of electric disturbances. An oscillation arising from a disturbance at a given generator site will affect the normal operation of neighbouring generators and might cause them to fail. Hours of production time will be lost in the time it takes to restart the power plant. If the disturbance is detected early, appropriate control measures can be applied to ensure system stability. The aim of this study is to improve existing algorithms that estimate the oscillation parameters from acquired generator data to detect potentially dangerous power system disturbances.
When disturbances occur in power systems (due to load changes or faults), damped oscillations (or "modes") are created. Modes which are heavily damped die out quickly and pose no threat to system stability. Lightly damped modes, by contrast, die out slowly and are more problematic. Of more concern still are "negatively damped" modes which grow exponentially with time and can ultimately cause the power system to fail. Widespread blackouts are then possible. To avert power system failures it is necessary to monitor the damping of the oscillating modes. This thesis proposes a number of damping estimation algorithms for this task. If the damping is found to be very small or even negative, then additional damping needs to be introduced via appropriate control strategies.
This thesis presents a number of new algorithms for estimating the damping of modal oscillations in power systems. The first of these algorithms uses multiple orthogonal sliding windows along with least-squares techniques to estimate the modal damping. This algorithm produces results which are superior to those of earlier sliding window algorithms (that use only one pair of sliding windows to estimate the damping). The second algorithm uses a different modification of the standard sliding window damping estimation algorithm - the algorithm exploits the fact that the Signal to Noise Ratio (SNR) within the Fourier transform of practical power system signals is typically constant across a wide frequency range. Accordingly, damping estimates are obtained at a range of frequencies and then averaged. The third algorithm applied to power system analysis is based on optimal estimation theory. It is computationally efficient and gives optimal accuracy, at least for modes which are well separated in frequency.
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Glickman, Mark. "Disturbance monitoring in distributed power systems." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16497/.
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Power system generators are interconnected in a distributed network to allow sharing of power. If one of the generators cannot meet the power demand, spare power is diverted from neighbouring generators. However, this approach also allows for propagation of electric disturbances. An oscillation arising from a disturbance at a given generator site will affect the normal operation of neighbouring generators and might cause them to fail. Hours of production time will be lost in the time it takes to restart the power plant. If the disturbance is detected early, appropriate control measures can be applied to ensure system stability. The aim of this study is to improve existing algorithms that estimate the oscillation parameters from acquired generator data to detect potentially dangerous power system disturbances. When disturbances occur in power systems (due to load changes or faults), damped oscillations (or "modes") are created. Modes which are heavily damped die out quickly and pose no threat to system stability. Lightly damped modes, by contrast, die out slowly and are more problematic. Of more concern still are "negatively damped" modes which grow exponentially with time and can ultimately cause the power system to fail. Widespread blackouts are then possible. To avert power system failures it is necessary to monitor the damping of the oscillating modes. This thesis proposes a number of damping estimation algorithms for this task. If the damping is found to be very small or even negative, then additional damping needs to be introduced via appropriate control strategies. This thesis presents a number of new algorithms for estimating the damping of modal oscillations in power systems. The first of these algorithms uses multiple orthogonal sliding windows along with least-squares techniques to estimate the modal damping. This algorithm produces results which are superior to those of earlier sliding window algorithms (that use only one pair of sliding windows to estimate the damping). The second algorithm uses a different modification of the standard sliding window damping estimation algorithm - the algorithm exploits the fact that the Signal to Noise Ratio (SNR) within the Fourier transform of practical power system signals is typically constant across a wide frequency range. Accordingly, damping estimates are obtained at a range of frequencies and then averaged. The third algorithm applied to power system analysis is based on optimal estimation theory. It is computationally efficient and gives optimal accuracy, at least for modes which are well separated in frequency.
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Trentini, Preuss Rodrigo [Verfasser]. "Contributions to the damping of interarea modes in extended power systems : a turbine governor approach with the help of the Unrestricted Horizon Predictive Controller / Rodrigo Trentini Preuss." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1136295828/34.
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Furini, Marcos Amorielle [UNESP]. "Estudo da estabilidade a pequenas perturbações de sistemas elétricos de potência multimáquinas sob a ação dos controladores FACTS TCSC e UPFC." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/87215.
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furini_ma_me_ilha.pdf: 1020610 bytes, checksum: d3a4a2f6ec4cb8559c7d3d6b770ec955 (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>O objetivo desta Dissertação de Mestrado é apresentar a possibilidade de fornecer amortecimento às oscilações de baixa freqüência do sistema elétrico de potência através dos dispositivos FACTS (Flexible Alternating Current Transmission System) TCSC (Thyristor Controlled Series Capacitor) e UPFC (Unified Power Flow Controller). Para isso realiza-se o desenvolvimento e implementação do Modelo de Sensibilidade de Potência para sistemas multmáquinas. Na seqüência são introduzidos os dispositivos TCSC e UPFC, bem como os seus controladores. Apresentam-se resultados de acordo com a evolução dos modelos que representam os dispositivos FACTS, ou seja, parte-se de uma compensação fixa, passando para um modelo dinâmico de primeira ordem e por fim, é incluído o controlador POD (Power Oscillation Damping). A utilização de sinais locais e remotos para entrada do controlador POD também é analisada. Além disso são mostrados os resultados obtidos pela técnica clássica de introdução de amortecimento através de sinais suplementares (os estabilizadores de sistemas de potência – PSS: Power System Stabilizers). O projeto dos controladores POD e PSS é baseado no método da compensação de fase, utilizando a teoria de controle clássico. Fatores de participação, autovetores, autovalores e resíduos de funções de transferência são utilizados como índices para examinar a melhor alocação dos controladores POD e PSS no sistema elétrico de potência.<br>The objective of this work is to present the possibility to provide damping to low frequencies oscillations of the electrical power systems by FACTS devices (Flexible Alternating Current Transmission System): TCSC (Thyristor Controlled Series Capacitor) and UPFC (Unified Power Flow Controller). This is developed and implemented using the Power Sensitivity Model for multimachine systems. Afterwards, the TCSC and UPFC devices are introduced as well as the controllers. Results are presented according to the evolution of the models that represent the FACTS devices, i.e., it starts with a fixed compensation, passing through a first order dynamic model and finally, it is included a POD controller (Power Oscillation Damping). It is also analyzed the inclusion of local and remote signals for the input of the POD controller. Besides, results obtained by classical techniques of introducing damping by supplementary signals (Power Systems Stabilizer – PSS) are shown. The project of POD and PSS controllers are based on the Phase Compensation Method using the classical control theory. Participation Factor like eigenvalues, eigenvectors and transfer function residues are used as index to examine the best allocation of the POD and PSS controllers on the electrical power systems.
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Furini, Marcos Amorielle. "Estudo da estabilidade a pequenas perturbações de sistemas elétricos de potência multimáquinas sob a ação dos controladores FACTS TCSC e UPFC /." Ilha Solteira : [s.n.], 2008. http://hdl.handle.net/11449/87215.
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Orientador: Percival Bueno de Araujo<br>Banca: Antonio Padilha Feltrin<br>Banca: Wellington Santos Mota<br>Resumo: O objetivo desta Dissertação de Mestrado é apresentar a possibilidade de fornecer amortecimento às oscilações de baixa freqüência do sistema elétrico de potência através dos dispositivos FACTS (Flexible Alternating Current Transmission System) TCSC (Thyristor Controlled Series Capacitor) e UPFC (Unified Power Flow Controller). Para isso realiza-se o desenvolvimento e implementação do Modelo de Sensibilidade de Potência para sistemas multmáquinas. Na seqüência são introduzidos os dispositivos TCSC e UPFC, bem como os seus controladores. Apresentam-se resultados de acordo com a evolução dos modelos que representam os dispositivos FACTS, ou seja, parte-se de uma compensação fixa, passando para um modelo dinâmico de primeira ordem e por fim, é incluído o controlador POD (Power Oscillation Damping). A utilização de sinais locais e remotos para entrada do controlador POD também é analisada. Além disso são mostrados os resultados obtidos pela técnica clássica de introdução de amortecimento através de sinais suplementares (os estabilizadores de sistemas de potência - PSS: Power System Stabilizers). O projeto dos controladores POD e PSS é baseado no método da compensação de fase, utilizando a teoria de controle clássico. Fatores de participação, autovetores, autovalores e resíduos de funções de transferência são utilizados como índices para examinar a melhor alocação dos controladores POD e PSS no sistema elétrico de potência.<br>Abstract: The objective of this work is to present the possibility to provide damping to low frequencies oscillations of the electrical power systems by FACTS devices (Flexible Alternating Current Transmission System): TCSC (Thyristor Controlled Series Capacitor) and UPFC (Unified Power Flow Controller). This is developed and implemented using the Power Sensitivity Model for multimachine systems. Afterwards, the TCSC and UPFC devices are introduced as well as the controllers. Results are presented according to the evolution of the models that represent the FACTS devices, i.e., it starts with a fixed compensation, passing through a first order dynamic model and finally, it is included a POD controller (Power Oscillation Damping). It is also analyzed the inclusion of local and remote signals for the input of the POD controller. Besides, results obtained by classical techniques of introducing damping by supplementary signals (Power Systems Stabilizer - PSS) are shown. The project of POD and PSS controllers are based on the Phase Compensation Method using the classical control theory. Participation Factor like eigenvalues, eigenvectors and transfer function residues are used as index to examine the best allocation of the POD and PSS controllers on the electrical power systems.<br>Mestre
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Ladjavardi, Marjan. "Improving small signal stability of power systems in the presence of harmonics." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/511.
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This thesis investigates the impact of harmonics as a power quality issue on the dynamic behaviour of the power systems. The effectiveness of the power system stabilizers in distorted conditions is also investigated. This thesis consists of three parts as follows:The first part focuses on the operation of the power system under distorted conditions. The conventional model of a synchronous generator in the dq-frame of reference is modified to include the impact of time and space harmonics. To do this, the synchronous generator is first modelled in the harmonic domain. This model helps in calculating the additional parts of the generator fundamental components due to the harmonics. Then the Park transformation is used for calculating the modified fundamental components of the synchronous generator in dq axes. The modified generator rotor angle due to the presence of harmonics is calculated and the impact of damper windings under the influence of harmonics is investigated. This model is used to study the small-signal stability of a distorted Single Machine Infinite Bus (SMIB) system. The eigenvalue analysis method is employed and the system state space equations are calculated by linearizing the differential equations around the operating point using an analytical method. The simulation results are presented for a distorted SMIB system under the influence of different harmonic levels. The impact of damper windings and also harmonics phase angles are also investigated.In the second part of the thesis, the effectiveness of the power system damping controllers under distorted conditions is studied. This investigation is done based on a distorted SMIB system installed with a Static Synchronous Series Compensator (SSSC). In the first step, the system state space equations are derived. A Power Oscillation Damping (POD) controller with a conventional structure is installed on the SSSC to improve the system dynamic behaviour. A genetic-fuzzy algorithm is proposed for tuning the POD parameters. This method along with the observability matrix is employed to design a POD controller under sinusoidal and distorted conditions. The impact of harmonics on the effectiveness of the POD controller under distorted conditions is investigated.In the last part, the steady state and dynamic operation of an actual distributed generation system under sinusoidal and distorted conditions are studied. A decoupled harmonic power flow program is employed for steady state analysis. The nonlinear loads are modelled as decoupled harmonic current sources and the nonlinear model of synchronous generator in harmonic domain is used to calculate the injected current harmonics. For the system dynamic stability study, the power system toolbox with the modified model of the synchronous generator is used. The system eigenvalues are calculated and the effectiveness of the installed Power System Stabilisers (PSS) is investigated under sinusoidal and distorted conditions. Simulation results show that in order to guarantee the effectiveness of a PSS in distorted conditions, it is necessary to consider the harmonics in tuning its parameters.
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Gamino, Bruno Rafael. "Análise da estabilidade a pequenas perturbações considerando a atuação dos controladores suplementares de amortecimento ESP e TCSC-POD ajustados por um algoritmo BVNS /." Ilha Solteira, 2018. http://hdl.handle.net/11449/157402.
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Orientador: Percival Bueno de Araujo<br>Resumo: Neste trabalho, uma técnica baseada na Busca em Vizinhança Variável Básica é apresentada para realizar o ajuste coordenado dos parâmetros dos controladores suplementares de amortecimento Thyristor Controlled Series Capacitor - Power Oscillation Damping e Estabilizadores de Sistemas de Potência, a fim de garantir a estabilidade a pequenas perturbações de sistemas elétricos de potência. A estratégia do método de ajuste proposto consiste em explorar sistematicamente estruturas de vizinhança atrelada a uma etapa de busca local, tornando possível a obtenção de soluções ótimas e a manutenção da capacidade de evitar a estagnação em um ótimo local. Um modelo do TCSC por injeção de corrente é apresentado e seus coeficientes de sensibilidade de corrente são deduzidos para incorporação ao Modelo de Sensibilidade de Corrente, que é utilizado para representar o sistema elétrico de potência. Com a inclusão da modelagem dos controladores de amortecimento, simulações são realizadas em dois sistemas testes, conhecidos como sistema Simétrico de Duas Áreas e sistema New England. Os resultados obtidos são analisados para melhor compreensão do comportamento do sistema elétrico de potência quando submetido a uma pequena perturbação e da influência dos controladores de amortecimento neste cenário. Os parâmetros dos controladores são ajustados pelo algoritmo Particle Swarm Optimization, por um Algoritmo Genético e, também, pelo método proposto neste trabalho. Os desempenhos individuais dos métodos d... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: In this work, a technique based on Basic Variable Neighborhood Search is presented to perform the coordinated tuning of the parameters of the supplementary damping controllers Thyristor Controlled Series Capacitor - Power Oscillation Damping and Power System Stabilizers in order to guarantee the small-signal stability of the electric power systems. The strategy of the proposed tuning method consists in systematically exploring neighborhood structures followed by a local search stage, making it possible to obtain optimal solutions and to maintain the ability to avoid stagnation in a local optimum. A current injection model for the TCSC is presented and its current sensitivity coefficients are deduced for incorporation into the Current Sensitivity Model, which is used to represent the electric power system. With the inclusion of the damping controllers modeling, simulations are performed on two test systems, known as the Two-Area Symmetric system and New England system. The results obtained are analyzed to better understand the behavior of the electric power system when subjected to a small disturbance and the influence of the damping controllers in this scenario. The controllers parameters are tuned by the Particle Swarm Optimization algorithm, by a Genetic Algorithm and also by the method proposed in this work. The individual performances of the tuning methods are compared in order to conclude on the technique best suited for this type of problem, including the analysis of a ... (Complete abstract click electronic access below)<br>Doutor
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Machado, Martínez Juan Eduardo. "Some Problems on the Analysis and Control of Electrical Networks with Constant Power Loads On Existence of Equilibria of Multi-Port Linear AC Networks With Constant-Power Loads An Adaptive Passivity-Based Controller of a Buck-Boost Converter with a Constant Power Load Power-Controlled Hamiltonian Systems: Application Electrical Systems with Constant Power Loads On the Existence and Long-Term Stability of Voltage Equilibria in Power Systems with Constant Power Loads Active Damping of a DC Network with a Constant Power Load: An Adaptive Observer-based Design." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS445.
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La croissante demande d'énergie électrique a conduit à la conception de systèmes électriques de grande complexité où les combustibles fossiles constituent la principale source d'énergie. Néanmoins, les préoccupations environnementales poussent à un changement majeur dans les pratiques de production d'électricité, avec un passage marqué des énergies fossiles aux énergies renouvelables et des architectures centralisées à distribuées. Les problèmes de stabilité dus à la présence de ce qu'on appelle les Charges à Puissance Constante (CPLs) constituent l’un des principaux défis auxquels sont confrontés les systèmes électriques distribués. On sait que ces charges, que l’on trouve couramment dans les installations de technologie de l’information et de la communication, réduisent l’amortissement effectif des circuits qui les alimentent, ce qui peut provoquer des oscillations de tension, voire une chute. Dans cette thèse, les principales contributions sont centrées sur la compréhension et la résolution de divers problèmes rencontrés dans l'analyse et le contrôle de systèmes électriques contenant des CPLs. Les contributions sont énumérées comme suit. (i) Des conditions simplement vérifiables sont proposées pour certifier la non existence d'états en régime permanent pour des réseaux multi-ports, à courant alternatif avec une distribution de CPLs. Ces conditions, qui reposent sur les inégalités matricielles linéaires, permettent d’écarter les valeurs des puissances des charges qui produiraient certainement un effondrement de la tension sur l’ensemble du réseau. (ii) Pour des modèles généraux de certains systèmes électriques modernes, y compris les réseaux de transmission à courant continu haute tension et les microréseaux, il est montré que, si des équilibres existent, il existe un équilibre caractéristique à haute tension qui domine tous les autres. En outre, dans le cas des systèmes d'alimentation en courant alternatif sous l'hypothèse de découplage standard, cet équilibre caractéristique s'avère stable à long terme. (iii) Une classe de systèmes port-Hamiltoniens, dans laquelle les variables de contrôle agissent directement sur l'équation du balance de puissance, est explorée. Il est démontré que ces systèmes sont décalés de manière passive lorsque leurs trajectoires sont contraintes à des ensembles facilement définissables. Ces dernières propriétés sont exploitées pour analyser la stabilité de leurs équilibres intrinsèquement non nuls. Il a également été montré que la stabilité des réseaux électriques à courant continu multiports et des générateurs synchrones, tous deux connectés à des CPLs, peuvent naturellement être étudiée avec le cadre proposé. (iv) Le problème de la régulation de la tension de sortie du convertisseur buck-boost alimentant une CPL non connu est résolu. L'un des principaux obstacles à la conception de commandes linéaires classiques provient du fait que le modèle du système est de phase non minimale par rapport à chacune de ses variables d'état. Cette thèse rapporte un contrôleur adaptatif non linéaire capable de rendre un équilibre souhaité asymptotiquement stable; de plus, une estimation de la région d'attraction peut être calculée. (v) La dernière contribution concerne l'amortissement actif d'un système d'alimentation de petite taille à courant continu avec une CPL. Au lieu de connecter des éléments passifs peu pratiques et énergétiquement inefficaces au réseau existant, l’ajout d’un convertisseur de puissance contrôlé est exploré. La contribution principale rapportée ici est la conception d'une loi de contrôle non linéaire basée sur l'observateur pour le convertisseur. La nouveauté de la proposition réside dans le fait qu'il n'est pas nécessaire de mesurer le courant électrique du réseau ni la valeur de la CPL, soulignant ainsi son applicabilité pratique. L'efficacité du schéma de contrôle est ensuite validée par des expériences sur un réseau à courant continu réel<br>The continuously increasing demand of electrical energy has led to the conception of power systems of great complexity that may extend even through entire countries. In the vast majority of large-scale power systems the main primary source of energy are fossil fuels. Nonetheless, environmental concerns are pushing a major change in electric energy production practices, with a marked shift from fossil fuels to renewables and from centralized architectures to more distributed ones. One of the main challenges that distributed power systems face are the stability problems arising from the presence of the so-called Constant Power Loads (CPLs). These loads, which are commonly found in information and communication technology facilities, are known to reduce the effective damping of the circuits that energize them, which can cause voltage oscillations or even voltage collapse. In this thesis, the main contributions are focused in understanding and solving diverse problems found in the analysis and control of electrical power systems containing CPLs. The contributions are listed as follows. (i) Simply verifiable conditions are proposed to certify the non existence of steady states in general, multi-port, alternating current (AC) networks with a distributed array of CPLs. These conditions, which are based on Linear Matrix Inequalities, allow to discard the values of the loads' powers that would certainly produce a voltage collapse in the whole network. (ii) For general models of some modern power systems, including High-Voltage Direct Current transmission networks and microgrids, it is shown that if equilibria exist, then there is a characteristic high-voltage equilibrium that dominates, entry-wise, all the other ones. Furthermore, for the case of AC power systems under the standard decoupling assumption, this characteristic equilibrium is shown to be long-term stable. (iii) A class of port-Hamiltonian systems, in which the control variables act directly on the power balance equation, is explored. These systems are shown to be shifted passive when their trajectories are constrained to easily definable sets. The latter properties are exploited to analyze the stability of their---intrinsically non zero---equilibria. It is also shown that the stability of multi-port DC electrical networks and synchronous generators, both with CPLs, can be naturally studied with the proposed framework. (iv) The problem of regulating the output voltage of the versatile DC buck-boost converter feeding an {em unknown} CPL is addressed. One of the main obstacles for conventional linear control design stems from the fact that the system's model is non-minimum phase with respect to each of its state variables. As a possible solution to this problem, this thesis reports a nonlinear, adaptive controller that is able to render a desired equilibrium asymptotically stable; furthermore an estimate of the region of attraction can be computed. (v) The last contribution concerns the active damping of a DC small-scale power system with a CPL. Instead of connecting impractical, energetically inefficient passive elements to the existing network, the addition of a controlled DC-DC power converter is explored. The main contribution reported here is the design of a nonlinear, observer-based control law for the converter. The novelty of the proposal lies in the non necessity of measuring the network's electrical current nor the value of the CPL, highlighting its practical applicability. The effectiveness of the control scheme is further validated through experiments on a real DC network
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Souza, Igor Dias Neto de. "Controle digital com malha dupla de tensão aplicado a um conversor formador de rede." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/4083.
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Previous issue date: 2017-02-17<br>Esta dissertação apresenta um estudo de um conversor emulador de rede (CER) que faz parte de uma estrutura Power-Hardware-in-the-Loop (PHIL). O PHIL será futuramente utilizado para verificar os impactos causados pela integração de sistemas de geração fotovoltaico (PV) à rede elétrica, assim como a operação do sistema PV frente a distúrbios na rede. O CER, composto por um conversor fonte de tensão (VSC) de dois níveis e filtro de saída LC, é responsável por alimentar cargas isoladas emulando uma rede elétrica. A modelagem do conversor emulador de rede é feita no sistema de coordenadas estacionário (αβ0), fornecendo um sistema de equações diferenciais usado para descrever o comportamento dinâmico do sistema. O conversor é controlado no modo de tensão, através da estratégia de modulação vetorial. Duas malhas de controle em cascata são projetadas. A malha interna utiliza compensadores em avanço digitais para amortecer a ressonância do filtro LC sem a necessidade de uma realimentação interna de corrente. Já a externa utiliza controladores ressonantes digitais modificados para rejeitar distúrbios harmônicos e garantir a qualidade da forma de onda da tensão no ponto de acoplamento comum. Os controladores ressonantes são conectados em série e o projeto é baseado no amortecimento dos zeros. Resultados experimentais, obtidos com o protótipo de laboratório, cujos controladores foram implementados em um processador digital de sinais TMS320F28335 da Texas Instruments, são usados para validar as estratégias de controle propostas.<br>This dissertation presents a study on a grid-former converter (GFC) which is a part of a Power-Hardware-in-the-Loop (PHIL) structure. The PHIL will be used to verify the impacts caused by the integration of photovoltaic (PV) generation systems into grid, as well as to study the PV operation under grid disturbances. The GFC, composed by a two-level voltage source converter with a LC output filter, is responsible to feed isolated loads emulating an electrical grid. The modeling of the grid-former converter is done in the stationary frame (αβ0), providing a set of differential equations that describes the dynamical behavior of the system. The converter is controlled in voltage mode by means of the space vector modulation (SVM) strategy. Two control loops are designed to control the static converter. At the inner loop a novel discrete-time active damping technique is proposed in order to damp the filter resonance without the need of current feedback. The method is based on an inner feedback loop with digital lead compensator on the feedback path while the external loop uses a discretetime integrator and a modified digital resonant controller to guarantee a decreasing frequency response and ensure the quality of the voltage waveform at the point of common coupling, respectively. The resonant controllers are connected in series and the design is based on its zeros damping. Experimental results obtained with the prototype, which controllers were implemented in a Texas Instruments TMS320F28335 are used to validate the proposed control strategies.
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Ajit, Kumar *. "Design Of Robust Power System Damping Controllers For Interconnected Power Systems." Thesis, 2010. https://etd.iisc.ac.in/handle/2005/1653.
Full textAbstract:
Small signal oscillation has been always a major concern in the operation of power systems. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, fluctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of these low frequency oscillations. Small oscillations in the range of about 0.1Hz to 3.5Hz can persist for long periods, limiting the power transfer capability of the transmission lines. Power System Stabilizers (PSS’s) were developed as auxiliary controllers on the generators excitation system to produce additional damping by modulating the generator excitation voltage. Designing effective PSS for all operating conditions specially in large interconnected power systems still remains a difficult and challenging task.
The conventionally designed Power System Stabilizer (CPSS) is the most cost-effective electromechanical damping controller till date. However, continual changes in the operating condition and network parameters in large systems result in corresponding large changes in system dynamics. This constantly changing nature of power system makes the design of CPSS a difficult task. The design and tuning of PSS for robust operation is a laborious process. The existing PSS design techniques require considerable expertise, the complete system information and extensive eigenvalue calculations which increases the computational burden as the system size increases.
This thesis proposes a method for designing robust power system damping controllers that ensures a minimum robustness under model uncertainties. The minimum performance required for the PSS is set a priori and accomplished over a range of operating conditions.
A generalized robust controller design methodology has been first implemented on a Single Machine Infinite Bus (SMIB) power system model. The robust controller places the closed loop rotor modes of the system to the desire location while keeping the electrical modes intact. Unlike conventional lead/lag PSS design, the proposed PSS design is based on pole assignment technique which takes into account of various model uncertainties.
For the proposed stabilizer design in a multi-machine systems a new decentralized method has been used which requires system data only upto secondary bus of the unit transformer in a generating station. The proposed robust controller design based on modified Nevanlinna-Pick theory has been designed and tested extensively on SMIB and multi-machine systems to establish the efficacy of the controller in damping small signal oscillations.
The thesis is organized in four chapters as follows.
The first chapter discusses the basic concepts related to the rotor angle stability in power system. The conventional and other methods of countering this instability by power system stabilizers have been described. The relative merits of the various stabilization techniques have been discussed. The scope of present work, i.e design of decentralized robust power system controllers has been defined.
In second chapter a modified robust power system stabilizer for SMIB system is developed. It has been shown that under specific conditions the modified Nevanlinna-Pick theory can also be applied for designing damping controllers in system with lightly damped rotor modes.
Third chapter proposes a decentralized approach based on modified Nevanlinna-Pick theory for designing a power system stabilizer for interconnected power systems. The performance of the controller which is not based on external system information has been investigated on three widely used multi-machine test systems to established its efficacy in damping out low frequency oscillations.
The fourth chapter gives a brief summary of the work done and also includes a section on the scope of future work relating to design of power system stabilizers.
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Ajit, Kumar *. "Design Of Robust Power System Damping Controllers For Interconnected Power Systems." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1653.
Full textAbstract:
Small signal oscillation has been always a major concern in the operation of power systems. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, fluctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of these low frequency oscillations. Small oscillations in the range of about 0.1Hz to 3.5Hz can persist for long periods, limiting the power transfer capability of the transmission lines. Power System Stabilizers (PSS’s) were developed as auxiliary controllers on the generators excitation system to produce additional damping by modulating the generator excitation voltage. Designing effective PSS for all operating conditions specially in large interconnected power systems still remains a difficult and challenging task.
The conventionally designed Power System Stabilizer (CPSS) is the most cost-effective electromechanical damping controller till date. However, continual changes in the operating condition and network parameters in large systems result in corresponding large changes in system dynamics. This constantly changing nature of power system makes the design of CPSS a difficult task. The design and tuning of PSS for robust operation is a laborious process. The existing PSS design techniques require considerable expertise, the complete system information and extensive eigenvalue calculations which increases the computational burden as the system size increases.
This thesis proposes a method for designing robust power system damping controllers that ensures a minimum robustness under model uncertainties. The minimum performance required for the PSS is set a priori and accomplished over a range of operating conditions.
A generalized robust controller design methodology has been first implemented on a Single Machine Infinite Bus (SMIB) power system model. The robust controller places the closed loop rotor modes of the system to the desire location while keeping the electrical modes intact. Unlike conventional lead/lag PSS design, the proposed PSS design is based on pole assignment technique which takes into account of various model uncertainties.
For the proposed stabilizer design in a multi-machine systems a new decentralized method has been used which requires system data only upto secondary bus of the unit transformer in a generating station. The proposed robust controller design based on modified Nevanlinna-Pick theory has been designed and tested extensively on SMIB and multi-machine systems to establish the efficacy of the controller in damping small signal oscillations.
The thesis is organized in four chapters as follows.
The first chapter discusses the basic concepts related to the rotor angle stability in power system. The conventional and other methods of countering this instability by power system stabilizers have been described. The relative merits of the various stabilization techniques have been discussed. The scope of present work, i.e design of decentralized robust power system controllers has been defined.
In second chapter a modified robust power system stabilizer for SMIB system is developed. It has been shown that under specific conditions the modified Nevanlinna-Pick theory can also be applied for designing damping controllers in system with lightly damped rotor modes.
Third chapter proposes a decentralized approach based on modified Nevanlinna-Pick theory for designing a power system stabilizer for interconnected power systems. The performance of the controller which is not based on external system information has been investigated on three widely used multi-machine test systems to established its efficacy in damping out low frequency oscillations.
The fourth chapter gives a brief summary of the work done and also includes a section on the scope of future work relating to design of power system stabilizers.
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Kumar, Ajit. "Enhancement of Small Signal Stability in Power Systems: Novel Approaches." Thesis, 2018. http://etd.iisc.ac.in/handle/2005/4157.
Full textAbstract:
The modern power system is a highly nonlinear system that operates in a constantly changing environment. Power system, need to maintain more or less flat voltage profile across the grid and maintain stability for small and large disturbances. Traditionally, automatic voltage regulators (AVR) are used for voltage regulation and power system stabilizers (PSS) are used as auxiliary controllers in AVR to enhance the small signal stability of power system.
The conventional PSS design techniques require considerable expertise, full system information and extensive eigenvalue calculations, which increase the computational complexity with the increase in system size. The thesis proposes a novel approach to design a fixed parameter PSS utilizing only the local system information applicable for a wide range of operating and system conditions. The phase compensation requirements for a fixed parameter PSS significantly change with the generator loading and topology which degrades the PSS performance. The thesis proposes to augment a nonlinear gain to the existing static AVR structure so that the impact of the loading conditions is completely eliminated. It is shown that this modification produces a single phase-compensation curve for all loading levels which simplifies the PSS design and eliminates the PSS tuning requirements.
If the coupling between the voltage loop and the rotor angle loop is removed then the conflicting nature between them can be eliminated. This thesis shows that the rotor dynamics and voltage dynamics can be decoupled in a synchronous machine using a partial feedback linearization based nonlinear AVR. However, in such cases the damping is only dependent on the natural damping in the system. So, PSS is needed even in the case of a nonlinear AVR if the natural damping is insufficient. Consequently, a PSS design for a single machine infinite bus (SMIB) power system with the nonlinear AVR is proposed. The PSS design using local information is also extended to the nonlinear AVR scenario in a multi machine environment.
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Nagesh, Prabhu *. "Analysis Of SubSynchronous Resonance With Voltage Source Converter Based FACTS And HVDC Controllers." Thesis, 2004. https://etd.iisc.ac.in/handle/2005/1174.
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Nagesh, Prabhu *. "Analysis Of SubSynchronous Resonance With Voltage Source Converter Based FACTS And HVDC Controllers." Thesis, 2004. http://etd.iisc.ernet.in/handle/2005/1174.
Full text
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Tambey, Neelima. "Flexible AC transmission systems (FACT) controllers for damping power system oscillations." Thesis, 2003. http://localhost:8080/xmlui/handle/12345678/5553.
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Sarkar, Mithu. "Robust Wide-Area Damping Controllers for compensating Inter-Area Oscillations in Power System." Thesis, 2019. http://ethesis.nitrkl.ac.in/10136/2/2019_PhD_MSarkar_514EE6034_Robust.pdf.pdf.
Full textAbstract:
Inter-area low-frequency oscillation is one of the major problems in an interconnected power system. The low frequency oscillations are observed to when a group of generators or a single generator on one side of the tie line oscillate against a group of generators or a single generator on the other side of the tie line. The power transfer capability through tie lies is reduced due to inter-area poorly damped oscillation. Sometimes these inter area oscillations may pose a serious threat to power system stability. Local signal based conventional power system stabilizer(PSS) is used to stabilize the low-frequency oscillation. However, due to the low observability of the local controller, these are not sufficient to provide adequate damping to the inter-area oscillation. A wide-area damping controller is efficient to provide adequate
damping to inter-area oscillation. Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations. Wide Area Measurement System(WAMS) is convenient to transmit the wide area signals by using a communication channel to a remote location. The operating condition of the power system changes very often hence a wide-area damping controller(WADC) should be designed such that perform in all operating condition. The focus of this research is to design centralized robust wide area damping controller for inter-area oscillations in power system. Proportional-Integral(PI) controller is one of the most popular controllers due to its simple structure to implement. Hence, a loop shaping based PI controller is designed to improve the damping of the inter-mode of oscillations. The gains of the PI controller are optimally determined by solving a convex optimization problem by employing the primal-dual interior point method. Although the wide-area signal can be used to obtain accurate dynamic behavior of power system, but time delay appears in the wide-area signal through transmission from a remote area to a controller site. Thus, there lies a great deal of challenge to design a suitable damping controller. A Unified Smith Predictor (USP) based loop shaping H¥ controller is then designed to compensate for the time delay effect by using wide-area signal. To achieve robust stabilization, the normalized coprime factor problem is converted into a generalized H¥ optimization problem satisfying additional pole placement constraints. Communication failure of the wide-area signal is another disastrous phenomenon that occurs in a communication channel. Hence, a Dual Input Single Output (DISO) H¥ controller is proposed to achieve the control resiliency by employing two highest observability ranking wide-area signals with respect to the critical damping inter-area mode. The proposed controller provides sufficient damping to the power system ensuring its stability even when one of the wide-area signal is lost. The involvement of time-delay in the wide-area signal transmission may deteriorate the controller performance. Hence, USP approach is adopted to design the H¥ controller with additional pole placement constraints to compensate a range of communication delay. Although the higher-order controller exhibits good damping performance, but its design remains always a challenge while implement is in the large power system. A speed-based fixed low-order Wide-Area Damping Controller (WADC) is proposed by using the non-convex and non-smooth optimization technique. The controller is synthesized by minimizing the objective function defined on the basis of the spectral abscissa, complex
stability radius, and H¥ norm minimization. The time delay effect is considered in the synchronized and non-synchronized feedback loop. The fixed low-order synchronized and non-synchronized WADC is proposed considering the delay in synchronized as well as in the non-synchronized feedback signals. The performances and effectiveness of all the above designed controllers namely loop shaping PI controller, USP based loop shaping H¥ controller, USP based DISO H¥ controller and fixed order H¥ controller have been verified by considering two case studies namely the Kundurs two-area system and IEEE-39 bus system considering different operating points. It is observed from small-signal analysis and time-domain simulation in MATLAB/Simulink that the proposed wide-area damping controllers provide adequate damping to inter-area oscillations and compensate for the adverse effect of the time delay. In addition, it is also observed that the proposed fixed low-order (2nd) wide-area damping controller provides slightly better damping performance than a higher order controller.
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Samal, S. K. "Power system stability enhancment using UPFC damping controller." Thesis, 2014. http://ethesis.nitrkl.ac.in/6126/1/e-72.pdf.
Full textAbstract:
The rising of demand of power and difficulties of constructing a newly transmission network causes the power system to be complex and stressed. Due to the stress in the power system there is a chance of losing the stability following to the fault. When the fault occurs in the power system the whole system goes to severe transients. By using PSS and AVR we can easily stabilize the system. FACTS devices (i.e. TCSC, SVC, STATCOM, and UPFC) are extremely important to suppressing the power system oscillations for faults and it also increasing the damping of the system. The power electronic device named as UPFC which efficiently control the active and reactive power. This thesis reflects a novel control technique which is based on Fuzzy Logic technique to provide external controlling signal to UPFC which is mounted in a single-machine infinite bus system to suppress low frequency oscillations and also it describes the model of a UPFC with multi-machine system which is externally controlled by the signal which is generated by the newly proposed power flow controller to increase the stability of the system with occurrence of fault in which it connected. The proposed controller consists of Power oscillation damping controller and Proportional Integral Differential controller (POD & PID). The effectiveness of controller for suppressing oscillation due to change in mechanical input and excitation is examined by investigating their change in rotor angle and speed occurred in the SMIB system. FACTS devices are used the existing transmission system very efficiently with the specified stability margin.
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Chonco, Nkosinathi Stanford. "The application of controllable inverter-based series compensation to power oscillation damping." Thesis, 2000. http://hdl.handle.net/10413/5601.
Full textAbstract:
Poorly damped oscillations that occur between the generators in large interconnected
power systems often limit the amount of power that can be transmitted through a
transmission corridor and are a threat to secure system operation. Coordinated
insertion and removal of capacitors in series with a transmission line is one of the
approaches that has been known for many years to be capable of enhancing the
damping of power system oscillations. Unfortunately however, this approach
historically relied on the operation of mechanical circuit breakers which were too
slow and unreliable for the high-speed and repetitive operation that such an
application demands. Recently-emerged, high-speed power-electronic-based
switching devices are finding increasing use in modem power systems in the so-called
Flexible AC Transmission Systems (F ACTS) concept. One particular FACTS
impedance controller, namely the inverter-based series compensator, can rapidly alter
the magnitude of capacitive compensating reactance in series with the line to make it
practically feasible to enhance the damping of power system oscillations via
dynamically-controlled series compensation.
This thesis identifies, in the literature, an insightful approach to the design of an
idealised controllable series compensator (CSC) damping scheme; such an approach
has been considered in the analyses of the thesis. Three mathematical models of a
single-machine infinite bus (SMIB) system are developed and are subsequently used
in the initial design and analysis of a CSC damping controller carried out in the thesis.
The simple SMIB system case study is used to identify and investigate the factors that
have a significant impact on the performance of a CSC damping controller before
studying the more complex issue of inter-area mode damping using a CSC.
This thesis successfully confirms the results of a previous analytical study in which an
idealised representation of the CSC was used, and extends the scope of that previous
study by also considering a detailed representation of one particular type of CSC: the
inverter-based series compensator. The two key findings of this extended
investigation are that the inverter-based form of controllable series compensator can
successfully be used to damp power oscillations and that, where the damping of oscillations is the particular focus of study, an idealised representation of the inverterbased
CSC is suitable for the analyses.
In the case of the inter-area mode damping problem, the selection of an appropriate
input signal to the CSC damping controller is a key issue, since the oscillations that
are to be damped involve a number of participating generators. This thesis examines
the suitability of a few candidate input signals that have been proposed in the
literature using the conceptually simpler SMIB system analytical models that have
been developed. Finally, the thesis applies the understanding of CSC damping
controller design gained from the SMIB study to the problem of inter-area mode
damping on a four-generator study system. Time-domain simulation results are
presented to demonstrate the impact of the controlled inverter-based series
compensator on the damping of the inter-area mode of this system.<br>Thesis (M.Sc.Eng.)-University of Natal, Durban, 2000.
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Kashyap, Ravi Bhushan. "Design of controllers associated with static VAR compensators for damping of low frequency oscillations in a power system." Thesis, 1993. http://spectrum.library.concordia.ca/2961/1/MM84663.pdf.
Full textAbstract:
This thesis is concerned with the development of a supplementary controller associated with a Static Var Compensator for damping of low-frequency oscillations (0.05-2.0 Hz) which are normally present in power systems. The objective of this thesis is to demonstrate that with the use of load modulation, damping of intermachine and system oscillation can be increased. The development of supplementary controllers requires that a simplified model of the system be available. In large systems this can be a difficult process. In this thesis a simplified approach is presented. It is based on fast fourier transform analysis of the response of the system in time domain from which a reduced order transfer function is determined. This analysis is carried out on a system similar to that of Hydro-Quebec. Classical control system design methods (root locus and bode plot) are then used to design the controller, limiting the analysis to the linear region. The extent of this region is defined in the thesis. The design of this controller is carried out and its effectiveness demonstrated in the environment of Matrix$\sb{\rm x},$ a mathematical software package. It is then confirmed for the detailed system using in-house transient stability program. The simulation results show the effectiveness of these controllers to damp the oscillations with the use of locally available variables. It is also shown that these controllers can be used to damp out the oscillations which may not be locally observable on the bus but are made available through the use of remote communication