Este trabalho propõe uma metodologia baseada em técnicas inteligentes capaz de fornecer uma coordenação otimizada de relés direcionais de sobrecorrente instalados em sistemas de energia elétrica. O problema é modelado como um caso de programação não linear inteira mista, em que os relés permitem ajustes discretizados de múltiplos de tempo e/ou múltiplos de corrente. A solução do problema de otimização correspondente é obtida através de uma metaheurística nomeada como Discrete Particle Swarm Optimization. Na literatura técnico-científica esse problema geralmente é linearizado e aplicam-se arredondamentos das variáveis discretas. Na metodologia proposta, as variáveis discretas são tratadas adequadamente para utilização na metaheurística e são apresentados os resultados que foram comparados com os obtidos pelo modelo clássico de otimização implementado no General Algebraic Modeling System (GAMS). Tendo em vista os aspectos observados, o método permite ao engenheiro de proteção ter um subsídio adicional na tarefa da coordenação dos relés direcionais de sobrecorrente, disponibilizando uma técnica eficaz e de fácil aplicabilidade ao sistema elétrico a ser protegido, independentemente da topologia e condição operacional. / This work proposes a methodology that based on intelligent technique to obtain an optimized coordination of directional overcurrent relays in electric power systems. The problem is modeled as a mixed integer nonlinear problem, because the relays allows a discrete setting of time and/or current multipliers. The solution of the proposed optimization problem is obtained from the proposed metaheuristic named as Discrete Particle Swarm Optimization. In scientific and technical literature this problem is usually linearized and discrete variables are rounded off. In the proposed method, the discrete variables are modeled adequately in the metaheuristic and the results are compared to the classical optimization solvers implemented in General Algebraic Modeling System (GAMS). The method provides an important method for helping the engineers in to coordinate directional overcurrent relays in a very optimized way. It has high potential for the application to realistic systems, regardless of topology and operating condition.

Este trabalho propõe uma metodologia baseada em técnicas inteligentes capaz de fornecer uma coordenação otimizada de relés direcionais de sobrecorrente instalados em sistemas de energia elétrica. O problema é modelado como um caso de programação não linear inteira mista, em que os relés permitem ajustes discretizados de múltiplos de tempo e/ou múltiplos de corrente. A solução do problema de otimização correspondente é obtida através de uma metaheurística nomeada como Discrete Particle Swarm Optimization. Na literatura técnico-científica esse problema geralmente é linearizado e aplicam-se arredondamentos das variáveis discretas. Na metodologia proposta, as variáveis discretas são tratadas adequadamente para utilização na metaheurística e são apresentados os resultados que foram comparados com os obtidos pelo modelo clássico de otimização implementado no General Algebraic Modeling System (GAMS). Tendo em vista os aspectos observados, o método permite ao engenheiro de proteção ter um subsídio adicional na tarefa da coordenação dos relés direcionais de sobrecorrente, disponibilizando uma técnica eficaz e de fácil aplicabilidade ao sistema elétrico a ser protegido, independentemente da topologia e condição operacional. / This work proposes a methodology that based on intelligent technique to obtain an optimized coordination of directional overcurrent relays in electric power systems. The problem is modeled as a mixed integer nonlinear problem, because the relays allows a discrete setting of time and/or current multipliers. The solution of the proposed optimization problem is obtained from the proposed metaheuristic named as Discrete Particle Swarm Optimization. In scientific and technical literature this problem is usually linearized and discrete variables are rounded off. In the proposed method, the discrete variables are modeled adequately in the metaheuristic and the results are compared to the classical optimization solvers implemented in General Algebraic Modeling System (GAMS). The method provides an important method for helping the engineers in to coordinate directional overcurrent relays in a very optimized way. It has high potential for the application to realistic systems, regardless of topology and operating condition.

Electric power systems are among the most complex man made systems on the world. Most of the time, they operate under quasi-steady state. With the ever increasing load demand and the advent of the deregulated power market recently, the power systems are pushed more often to operate close to their design limits and with more uncertainty of the system operating mode. With the increasing complexity and more interconnected systems, power systems are operating closer to their performance limits. As a result, maintaining system security and facilitating efficient system operation have been challenging tasks. Transmission systems are considered the most vital components in power systems connecting both generating/substation and consumer areas with several interconnected networks. In the past, they were owned by regulated, vertically integrated utility companies. They have been designed and operated so that conditions in close proximity to security boundaries are not frequently encountered. However, in the new open access environment, operating conditions tend to be much closer to security boundaries, as transmission use is increasing in sudden and unpredictable directions. Transmission unbundling, coupled with other regulatory requirements, has made new transmission facility construction more difficult. Unfortunately these transmission lines are frequently subjected to a wide variety of faults. Thus, providing proper protective functions for them is essential. Generally the protection of Extra High Voltage (EHV) and Ultra High Voltage (UHV) transmission lines are carried out by the use of distance relays in view of the fact that they provide fast fault clearance and system coordination. Transmission line relaying involves detection, classification and location of transmission line faults. Fast detections of faults enable quick isolation of the faulty line from service and hence, protecting it from the harmful effects of fault. Classification of faults means identification of the type of fault and faulted line section, and this information is required for finding the fault location and assessing the extent of repair work to be carried out. Accurate fault location is necessary for facilitating quick repair and restoration of the line, to improve the reliability and availability of the power supply. Generally, the protection system using conventional distance relaying algorithm involves three zones. The first zone (Z1) of the relay is set to detect faults on 80%90% of the protected line without any intentional time delay. The second zone (Z2) is set to protect the remainder of the line plus an adequate margin. Second zone relays are time delayed for 1530 cycles to coordinate with relays at remote bus. The settings of the third zone (Z3) ideally will cover the protected line, plus all of the longest line leaving the remote station. Z3 of a distance relay is used to provide the remote backup protection in case of the failure of the primary protection. Since Z3 covers an adjacent line, a large infeed (outfeed) from the remote terminal causes the relay to underreach (overreach). Thus, a very large load at the remote terminal may cause distance relays to mal-operate. Settings for conventional distance relays are selected to avoid overreach/underreach operation under the worst case scenarios. Studies of significant power system disturbances reported by North American Electric Reliability Council (NERC) indicate that protective relays are involved, one way or another, in 75% of the major disturbances and the most troublesome ones are backup protection relays. With their limited view of the interconnected network based on their locally measured inputs, conventional backup protection relays generally take actions to protect a localized region of the network without considering the impact on the whole network. Relay mal-operations or unintended operations due to overload, power swing, and relay hidden failure are the main factors contributing to the blackouts. Most of the problems are associated with relays tripping too many healthy lines. Since a relay makes the decision automatically to remove a component from the system according to its internal mechanism, the relay mal-operation or unintended operation can make an effective influence on the system stability. Approaches to reduce the relay misbehavior need to be identified. Real time monitoring tools to assess the relay misbehavior are needed, providing the system operator, the accurate information about unfolding events. Existing transmission line protection scheme still has drawbacks. Advanced fault analysis mechanism to enhance the system dependability and security simultaneously is desirable. Relay settings play a significant role in major blackouts. So correct settings should be calculated and coordinated by suitable studies. Attempts are to be made to employ highly accurate AI techniques in protective system implementation. The research work focussed on developing knowledge based intelligent tools for the improving the transmission system security. A process to obtain knowledgebase using SVMs for ready post-fault diagnosis purpose is developed. SVMs are used as Intelligent tool for identifying the faulted line that is emanating from a substation and finding the distance from the substation. The approach uses phasor values of the line voltages and currents after the fault has been detected. The approach is particularly important for post-fault diagnosis of any mal-operation of relays following a disturbance in the neighboring line connected to the same substation. This may help in improving the fault monitoring/diagnosis process and coordination of the protective relays, thus assuring secure operation of the power systems. The approach based on SVMs, exploits the first part of this goal. For comparison, a classifier and regression tools based on the RBFNNs was also investigated. The RBFNNs and SVM networks are introduced and considered as an appropriate tool for pattern recognition problems. Results on a practical 24Bus equivalent EHV transmission system of Indian Southern region and on IEEE39 bus New England system are presented to illustrate the proposed method. In a large connected power network, the number of generators are more in number and their set patterns number will be large. As the line flows are sensitive to generator set patterns, it is difficult to consider all the combinations of generators while simulating the training and testing patterns as input to SVMs. To simulate the training and testing patterns corresponding to possible changes in line flows to meet the load in the present deregulated environment, line flow sensitive generators set to be identified/merit-listed. In this regard, to identify the most sensitive generators for a particular line of interest, a method from the literature is adopted and developed a software program based on the graph theory concepts. Case studies on generator contributions towards loads and transmission lines are illustrated on an equivalent 33bus system, a part of Indian Northern grid with major part of Uttar Pradesh and also with an equivalent 246bus system of practical Indian Southern grid. A distance relay coordination approach is proposed using detailed simulation studies, taking into account various operating conditions and fault resistances. Support Vector Machines as a pattern classifier is used for obtaining distance relay coordination. The scheme uses the apparent impedance values observed during fault as inputs. SVMs are used to build the underlying concept between reach of different zones and the impedance trajectory during fault. An improved performance with the use of SVMs, keeping the reach when faced with different fault conditions as well as line flow changes are illustrated with an equivalent 246bus system of practical Indian Southern grid and also with an equivalent 265bus system of practical Indian Western grid. A strategy of Supportive System is described to aid the conventional protection philosophy in combating situations where protection systems are mal-operated and/or information is missing and provide selective and secure coordination. Highly accurate identification/discrimination of zones plays a key role in effective implementation of the region-wide supportive system. This typically requires a multiclass SVM classifier to effectively analyze/build the underlying concept between reach of different zones and the apparent impedance trajectory during fault. Different multiclass methods are compared for their performance with respect to accuracy, number of iterations, number of support vectors, training and testing time. The performance analysis of these methods is presented on three data sets belonging to the training and testing patterns of three supportive systems for a region, part of a network, which is an equivalent 265bus system of practical Indian Western grid.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-08-13T16:41:07Z No. of bitstreams: 1 FRANCISCO DAS CHAGAS SOUZA JÚNIOR – TESE (PPGEEI) 2016.pdf: 4537364 bytes, checksum: 1696c9bd2456c0caad5ee6e61bcb7ca4 (MD5) / Made available in DSpace on 2018-08-13T16:41:07Z (GMT). No. of bitstreams: 1 FRANCISCO DAS CHAGAS SOUZA JÚNIOR – TESE (PPGEEI) 2016.pdf: 4537364 bytes, checksum: 1696c9bd2456c0caad5ee6e61bcb7ca4 (MD5) Previous issue date: 2016-07-05 / Uma técnica auto-adaptativa que torna a obtenção dos ajustes de coordenação de relés de sobre corrente instantânea para sistemas de distribuição uma tarefa automática, sem a necessidade de intervenção humana e nem a interrupção do fornecimento de energia elétrica ou do monitoramento da rede é proposta. Usando uma arquitetura distribuída, formada por três camadas conectadas através de canal de comunicação, modificações topológicas como entrada/saída de linhas, e/ou nos perfis de carga e geração do sistema elétrico terão seus efeitos automaticamente refletidas nos ajustes dos dispositivos de proteção. O método proposto usa a corrente de carga como item principal para a determinação dos ajustes das unidades instantâneas de sobre corrente em redes de distribuição de média tensão com e sem apresentação geração distribuída. Por meio do cálculo online dos equivalentes de rede a técnica proposta necessita de baixos níveis de intervenção humana para a realização dos estudos de coordenação e seletividade. Os resultados obtidos comprovam a viabilidade técnica da metodologia proposta e corrobora com o estado da arte no tocante ao desenvolvimento das redes elétricas inteligentes. / A self-adaptive technique that improves the instantaneous overcurrent relay settings determination an automatic task, without human intervention neither interruption on electric supply or grid monitoring is proposed. An architecture designed by three layers connected using a communication channel provides that modificationon power electric grid as connection/disconnection of transmissionlines, and/or on generator or load profiles will be automatically reflected on protective device settings. Load current has been used to determine the reach of instantaneous over current relay settings in a médium voltage distribution system considering cases with and without distributed generation connected on the grid. The possibility of online determination at Thevenin equivalent circuit low human interventions to execute coordination study. Obtained results demonstrate the viability of proposed technique an dincrease with state of art a bout improvements of smart electric grids.

This study concerns frequency relays and voltage relays applied to the protection of synchronous distributed generators operating in reactive power control mode without a frequency regulation function. The effect of active and reactive powers combination, load power factor, and reactive power imbalance are investigated for their implication for the anti-islanding setting of the frequency relay. Results reveal that the effect of these factors must be considered when setting the relay for islanding detection. For the voltage relay, results reveal that the effect of active and reactive powers combination, load power factor, and active power imbalance must be considered when setting the relay for islanding detection. The effect of multi-stage tripping on the frequency relay ability to detect island was also investigated. Results show that multistage tripping can improve the anti-islanding performance of the frequency relay. / Electrical Engineering / M. Tech. (Electrical Engineering)

Atualmente existem diferentes ferramentas computacionais para auxílio nos estudos de coordenação da proteção, que permitem traçar as curvas dos relés, de acordo com os parâmetros escolhidos pelos projetistas. Entretanto, o processo de escolha das curvas consideradas aceitáveis, com um elevado número de possibilidades e variáveis envolvidas, além de complexo, requer simplificações e iterações do tipo tentativa e erro. Neste processo, são fatores fundamentais tanto a experiência e o conhecimento do especialista, quanto um árduo trabalho, sendo que a coordenação da proteção é qualificada pela IEEE Std. 242 como sendo mais uma arte do que uma ciência. Este trabalho apresenta o desenvolvimento de um algoritmo genético e de um algoritmo inspirado em otimização por colônia de formigas, para automatizar e otimizar a coordenação da função de sobrecorrente de fase de relés digitais microprocessados (IEDs), em subestações industriais. Seis estudos de caso, obtidos a partir de um modelo de banco de dados, baseado em um sistema elétrico industrial real, são avaliados. Os algoritmos desenvolvidos geraram, em todos os estudos de caso, curvas coordenadas, atendendo a todas as restrições previamente estabelecidas e as diferenças temporais de atuação dos relés, no valor de corrente de curto circuito trifásica, apresentaram-se muito próximas do estabelecido como ótimo. As ferramentas desenvolvidas demonstraram potencialidade quando aplicadas nos estudos de coordenação da proteção, tendo resultados positivos na melhoria da segurança das instalações, das pessoas, da continuidade do processo e do impedimento de emissões prejudiciais ao meio ambiente. / Nowadays there are several computational tools applied to the protection coordination studies, which allow observe the curves of the relays, according to the parameters chosen by the designers. However, the process of choosing the curves considered acceptable, with a great number of possibilities and variables involved, is difficult and, moreover, requires simplifications and some trial and error iterations. In this process, the key factors are the expert experience and knowledge as well as a hard work. The protection coordination is described by IEEE Std. 242 as more of an art than a science. This paper presents the development of a genetic algorithm and an algorithm based on an ant colony optimization to automate and optimize the coordination of overcurrent curves using intelligent electronic devices (IEDs) in industrial substations. Six case studies, obtained from a database model based on an actual industrial electrical system, were evaluated. The developed algorithms generated, in all case studies, coordinated curves, complying with all previous established restrictions. The temporal differences of the curves, at three-phase short circuit current values, were very close to the set as optimal. The developed tools are a valuable contribution to the protection coordination studies, improving the safety of the equipment and the people, the process reliability and the prevention of harmful emissions to the environment.

Com novas normas, incentivos governamentais e preocupação com questões ambientais, é esperado um crescimento no número de unidades de geradoras conectadas a rede a partir dos consumidores. Algumas questões técnicas relacionadas à elevada penetração de geração distribuída nos alimentadores de distribuição preocupam as concessionárias de energia, as quais buscam meios de prevenir possíveis efeitos indesejados no sistema elétrico. Esta pesquisa apresenta o desenvolvimento de um relé digital aplicado à proteção da conexão de geração distribuída na rede elétrica, com foco em microgeração e minigeração proveniente de geradores síncronos, assíncronos e inversores. O relé digital contempla as principais funções de proteção exigidas pelos procedimentos e normas de acesso nacionais, incluindo algoritmos anti-ilhamento. O seu funcionamento se dá pela medição das grandezas elétricas no ponto de conexão entre a geração distribuída e a rede elétrica, filtragem digital dos sinais e processamento dos algoritmos das funções de proteção. Como num relé digital convencional, as funções de proteção podem ser configuradas individualmente, permitindo construção de expressões lógicas e de bloqueio. O protótipo pode ser monitorado e controlado localmente, através de uma aplicação instalada em um computador e utilizando a rede Ethernet. O protótipo permite controle remoto pela concessionária através de uma rede de telecomunicação em malha instalada no sistema elétrico de distribuição, utilizando protocolo ZigBee. É apresentada uma revisão bibliográfica sobre os efeitos e os problemas da geração distribuída no sistema elétrico, contextualizando o futuro das nossas redes de distribuição em relação a situação de países mais desenvolvidos nesse tema. Em seguida, são apresentadas as principais técnicas de processamento digital de sinais para relés digitais e o funcionamento das funções de proteção. Os detalhes do desenvolvimento do hardware, estratégias para filtragem digital e implementação dos algoritmos de proteção são apresentados. Algumas técnicas no algoritmo de filtragem e nas funções de proteção, como a medição de frequência trifásica utilizando a transformada de Clarke, são discutidas e avaliadas. Os resultados dos testes de funcionamento do protótipo, realizados em laboratório, são apresentados. Concluiu-se que o relé digital contempla um conjunto de proteções que abrange as principais normas para o acesso de geração distribuída no Brasil, pode ser utilizado como proteção de retaguarda para sistemas já dotados de proteções internas, como inversores, além de possibilitar o controle remoto de geração distribuída através da rede de telecomunicação em malha com protocolo ZigBee. / With new standards, government incentives and concerns about environmental questions, is expected the growth of the number of generating units connected to the grid from consumers. Some technical issues related to the high penetration of distributed generation on distribution feeders concerns the power utilities, which look for solutions to prevent possible unwanted effects on the electrical system. This research presents the development of a digital relay applied to protect the interconnection of distributed generation in the grid, focusing on micro and mini electricity generation plants from synchronous and asynchronous generators, and inverters. The digital relay contains the main protection functions required by PRODIST and utilities standards, including anti-islanding algorithms. Its operation is given by the measurement of electrical parameters at the point between the distributed generation and grid, followed by digital signal filtering and protection algorithms processing. Like a conventional digital relay, the protection functions can be individually configured, it’s possible to build logical and blocking expressions with them. The prototype can be monitored and controlled by a personal computer connected in the same local network. The computer must run an interface program. The prototype allow remote control by the utilities, this communication is done by a mesh network installed along the electric distribution system, using the ZigBee protocol. It’s presented a review about the effects and problems caused in the electrical power system by the distributed generation, giving the context of the future Brazilian distribution network in relation to the actual situation of more experienced countries on distributed generation. Following, it’s presented the main technics of digital signal processing applied to digital relays and operation of the protection functions. So then, the details of the hardware development, digital filtering strategies and the implementation of the protection algorithms are presented. Some technics applied to the filtering algorithms and protection function, as the three-phase frequency measurement using Clarke’s transformation, are discussed and evaluated. The test results of the prototype operation are presented, the tests were done in laboratory. The digital relay contain a set of protection functions that covers the main standards of distributed generation access in Brazil, it’s possible to use as a backup protection for systems with protections embedded, as grid tie inverters, and the possibility of remote control of distributed generation through the mesh network with ZigBee protocol.

Atualmente existem diferentes ferramentas computacionais para auxílio nos estudos de coordenação da proteção, que permitem traçar as curvas dos relés, de acordo com os parâmetros escolhidos pelos projetistas. Entretanto, o processo de escolha das curvas consideradas aceitáveis, com um elevado número de possibilidades e variáveis envolvidas, além de complexo, requer simplificações e iterações do tipo tentativa e erro. Neste processo, são fatores fundamentais tanto a experiência e o conhecimento do especialista, quanto um árduo trabalho, sendo que a coordenação da proteção é qualificada pela IEEE Std. 242 como sendo mais uma arte do que uma ciência. Este trabalho apresenta o desenvolvimento de um algoritmo genético e de um algoritmo inspirado em otimização por colônia de formigas, para automatizar e otimizar a coordenação da função de sobrecorrente de fase de relés digitais microprocessados (IEDs), em subestações industriais. Seis estudos de caso, obtidos a partir de um modelo de banco de dados, baseado em um sistema elétrico industrial real, são avaliados. Os algoritmos desenvolvidos geraram, em todos os estudos de caso, curvas coordenadas, atendendo a todas as restrições previamente estabelecidas e as diferenças temporais de atuação dos relés, no valor de corrente de curto circuito trifásica, apresentaram-se muito próximas do estabelecido como ótimo. As ferramentas desenvolvidas demonstraram potencialidade quando aplicadas nos estudos de coordenação da proteção, tendo resultados positivos na melhoria da segurança das instalações, das pessoas, da continuidade do processo e do impedimento de emissões prejudiciais ao meio ambiente. / Nowadays there are several computational tools applied to the protection coordination studies, which allow observe the curves of the relays, according to the parameters chosen by the designers. However, the process of choosing the curves considered acceptable, with a great number of possibilities and variables involved, is difficult and, moreover, requires simplifications and some trial and error iterations. In this process, the key factors are the expert experience and knowledge as well as a hard work. The protection coordination is described by IEEE Std. 242 as more of an art than a science. This paper presents the development of a genetic algorithm and an algorithm based on an ant colony optimization to automate and optimize the coordination of overcurrent curves using intelligent electronic devices (IEDs) in industrial substations. Six case studies, obtained from a database model based on an actual industrial electrical system, were evaluated. The developed algorithms generated, in all case studies, coordinated curves, complying with all previous established restrictions. The temporal differences of the curves, at three-phase short circuit current values, were very close to the set as optimal. The developed tools are a valuable contribution to the protection coordination studies, improving the safety of the equipment and the people, the process reliability and the prevention of harmful emissions to the environment.

Made available in DSpace on 2014-12-17T14:55:18Z (GMT). No. of bitstreams: 1 ArrheniusVCO_da_capa_ate_pag_12.pdf: 7828798 bytes, checksum: b0f0c76e1aebc32a2155c024e0abc8a9 (MD5) Previous issue date: 2004-12-17 / The objective of the present work is develop a model to simulate electrical energy networks in transient and stead states, using the software ATP (Alternative Transient Program), able to be a way to join two distinct themes, present in classical methodology planning networks: short circuit analysis and load flow theory. Beyond that, using a tool for relay simulation, this paper intend to use the new developed model to investigate the influence of transient phenomenon in operation of protection relays, and calibrate the enterprise's protections relays. For testing the model, some relays, actually, installed at COSERN were used / O presente trabalho objetiva ao desenvolvimento de um modelo para simular redes de energia el?trica em regimes transit?rio e permanente, utilizando o software ATP (Alternative Transient Program), para servir como elo entre dois temas distintos, presentes na metodologia cl?ssica de planejamento de redes: a an?lise de curtos-circuitos e o estudo de fluxo de carga. Al?m disso, dispondo de uma ferramenta de simula??o de rel?s, pretende-se usar o novo modelo, tanto para averiguar a influ?ncia de fen?menos transit?rios na opera??o dos rel?s de prote??o, quanto para calibrar esses rel?s. Para testar o modelo, utilizaram-se alguns dos rel?s atualmente instalados na COSERN