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Ntwoku, Stephane Ntuomou. "Dynamic transformer protection a novel approach using state estimation." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45879.
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Transformers are very important parts of any electrical network, and their size increase so does their price. Protecting these important devices is a daunting task due to the wide variety of operating conditions. This thesis develops a new protection scheme based on state estimation.The foundation upon which our protection scheme is built is the modeling of the single phase transformer system of equations. The transformer equations are composed of polynomial and differential equations and this system of equations involving the transformer's electrical quantities are modeled into a system of equations such that highest degree of each of the system's equations is quadratic―in a process named Quadratization and then integrated using a technique called Quadratic integration to give a set of algebraic companion equations that can be solved numerically to determine the health of the transformer.
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Yuping, Lu. "Intelligent technique based digital differential protection for generator-transformer unit." Thesis, City University London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410150.
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Strapko, Miroslav. "Návrh systému chránění s použitím elektronických přístrojových transformátorů (senzorů) v rozvodně vysokého napětí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219395.
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Master's thesis deals with use of electronic instrument transformers (sensors) in the protection system in medium-voltage substation. Substation consists of 2 incoming feeders, 2 outgoing feeders for motors, 2 outgoing feeders for power transformers, measuring, bus coupler and bus riser feeder. Incoming feeders are connected to distribution system E.ON by cable lines which were proposed. Protected machines (power transformers and motors with rated power) are connected to switchgear panels of UniGear ZS1 type by cable lines too. Proposed protection system is based on the short-circuit conditions, standard CSN 33 3051 recommendations as well as theoretical backgrounds acquired from technical papers and other publicated literature according to the bibliography. For selected protection functions are defined their parameters. Control, monitoring and protection functions provides REF 542plus relay. Consequently, secondary tests which are part of the commissioning, are given in the practical part of thesis. Secondary tests were performed by relay test system FREJA 300 by Megger. Results of tests are displayed in tripping characteristics.
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Assumpção, Felipe Framil. "Validation of Results of Smart Grid Protection through Self-Healing." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7468.
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This is a verification of the results of “Smart Grid Protection through Self-Healing” from the publication of Chathurika Chandraratne, et al., that proposes a protection solution for the smart grid. The paper used as reference has as the main focus on three different protections; directional overcurrent protection, overcurrent protection, and transformer protection, which are validated through ETAP software simulation of IEEE- 9 bus and 14 bus electrical power systems, the same used by the author. It was validated after repeated simulation, that just as intended, self-healing increases system agility, and it helped prevent false-tripping14 bus electrical power systems.
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Pieters, Willem Diederick. "Monitoring, protection, and voltage control of parallel power transformers based on IEC 61850-9-2 process bus." Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/3067.
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Thesis (MEng (Electrical Engineering)--Cape Peninsula University of Technology, 2019The purpose of an electrical power system is to supply electrical energy to the customers. Power transformers are required to transform the system voltage from generation to transmission and distribution levels. Protection and control systems must ensure that power system high voltage equipment such as transformers operate and deliver save, reliable and secure electricity supply. The aim of the project research work is to develop and implement a strategy, methods and algorithms for monitoring, protection and voltage control of parallel power transformers based on IEC 61850-9-2 process bus standard. NamPower is a power utility in Namibia. The IEC 61850 protocol for electrical substation automation system is used for the protection and control of 5 power transformers operated in parallel in an existing substation system. The IEC 61850-9-2 process bus standard is however not used in regards of Sampled Values (SV). Protection and control devices are connected to a substation communication network, routers and switches using fibre optic linked Ethernet. Inductive Current Transformers (CTs) and Voltage Transformers (VTs) secondary circuits are hardwired to Intelligent Electronic Devices (IEDs) and fibre optic links are not used for this purpose at process level communication. The research focuses on the implementation of the IEC 61850 standard with Merging Units (MUs) and sampled values to improve the existing implemented protection and control system at NamPower. This includes substation communication networks and MUs used for transformer protection, voltage regulator control and cooling fan control. At the present the CTs located at the transformer bushings and switchgear and the VTs located at the switchgear are hardwired to the inputs on protection and control IEDs. The research focuses on issues with the copper wires for voltage and currents signals and how these issues can be eliminated by using the MUs and the SV protocol. The MUs which are considered in this Thesis is to improve the voltage regulator control and the control of the cooling fan motors. The voltage regulator control IED is situated at the tap change motor drive of the On-Load Tap Changer (OLTC). The IED of each transformer is required to regulate the voltage level of the secondary side bus bar it is connected to. All the regulating IEDs are required to communicate with each other and collectively to control the bus bar voltage depending on the switching configuration of the parallel transformers. The control circuit for controlling the cooling fan motors is hardwired. Temperature analogue signal input into a programmable automation controller IED can be used for controlling the transformer cooling fans. A strategy, methods and algorithms for transformer protection, voltage regulator control and cooling fan motor control of parallel power transformers need to be developed and implemented based on IEC 61850-9-2 process bus. Power utilities and distributors can benefit from interpretation of the IEC 61850-9-2 standard and implementing MUs and SV in substations. MUs can be included in the power transformer protection, automation and control systems. A cost reduction in high voltage equipment, substation installation and commissioning costs and better performance of protection and control system are anticipated.
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Oliveira, Mario Orlando. "Proteção diferencial de transformadores trifásicos utilizando a transformada wavelet." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/17292.
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A qualidade e a continuidade do fornecimento de energia elétrica aos consumidores são fatores muito importantes quando da avaliação da eficiência de um sistema elétrico de potência. Nesse contexto, os transformadores são equipamentos muito importantes e demandam especial atenção quando do projeto do esquema de proteção. Apesar do crescente desenvolvimento das metodologias de proteção de transformadores trifásicos, alguns aspectos ainda não foram totalmente solucionados. Um desses diz respeito à proteção diferencial de transformadores de potência, a qual apresenta vários problemas na discriminação de faltas internas ao transformador. A geração de correntes diferenciais provocada por fenômenos transitórios, como a energização do transformador, produz a incorreta operação do relé, ocasionando uma queda na eficiência do esquema de proteção diferencial. Assim sendo, o presente trabalho apresenta uma nova metodologia de proteção diferencial de transformadores trifásicos, a qual utiliza a transformada wavelet para extrair os sinais transitórios dominantes induzidos pelas faltas internas. A transformada wavelet é uma eficiente ferramenta utilizada no estudo de sinais não-estacionários e de rápida transição. De forma a atender os principais problemas do esquema convencional de proteção, a transformada wavelet discreta é utilizada para decompor os sinais de corrente diferencial em várias faixas de freqüências. Após essa decomposição, a variação de energia espectral dos coeficientes de detalhe wavelet é analisada pelo algoritmo proposto, e assim uma discriminação entre faltas internas e correntes de magnetização, ou correntes inrush, é feita. Usando um modelo elaborado de um sistema elétrico de transmissão são efetuadas rigorosas simulações computacionais para avaliar o desempenho do algoritmo proposto. Os resultados obtidos nessas simulações mostram que a metodologia de proteção diferencial de transformadores trifásicos baseada na variação de energia espectral dos coeficientes wavelets apresenta um ótimo desempenho quando comparada com a metodologia de proteção convencional.Power supply quality and continuity are very important aspect when assessing the efficiency of an electric power system. In this context, the transformers are key equipments that require special attention during the protection scheme design. Despite the increasing development of methodologies for three-phase transformers protection, some aspects have not yet been fully studied. One of these aspects concerns to the differential protection of power transformers, which presents several restrictions regarding the characterization of internal faults. The observation of differential currents caused by transient phenomena such as transformer energization, produces an incorrect operation of protective relaying, causing a drop in the protection scheme efficiency. Therefore, this work presents a new methodology for differential protection of three-phase transformers using the wavelet transform to extract the transient signals induced by the dominant internal faults. The wavelet transform is an efficient tool in the study of non-stationary signals with fast transients. In order to overcome the main problems of the traditional protection scheme, the discrete wavelet transform is used to decompose the differential current signals into several bands of frequencies. After this decomposition, the spectral energy variation of the wavelet detail coefficients is analyzed by the proposed algorithm and, thus, classification between internal faults, external faults and inrush currents is performed. Using a transmission system model, accurate simulations are performed to evaluate the computational performance of the proposed protection algorithm. The results obtained in these simulations show that the proposed methodology has a great performance when compared with traditional protection philosophies.
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Oliveira, Mario Orlando. "Proteção diferencial adaptativa de transformadores de potência baseada na análise de componentes wavelets." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/87355.
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Este trabalho fundamenta-se no desenvolvimento e aprimoramento de uma metodologia de proteção diferencial de Transformadores de Potência. A metodologia desenvolvida avalia eventos transitórios que dificultam a operação correta de relés diferenciais aplicados à proteção de transformadores. O estudo concentra-se no estabelecimento de contribuições ao estado da arte associadas à análise de sinais de corrente diferenciais geradas tanto por faltas internas e externas quanto por distúrbios transitórios. A concepção da metodologia proposta baseou-se na quantificação da energia espectral gerada a través dos coeficientes de detalhe da Transformada Wavelet Discreta. A metodologia de proteção proposta foi desenvolvida em ambiente MATLAB® e testada por meio de simulações realizadas através do software ATP/EMTP (Alternative Transients Program/Electromagnetic Transients Program). Os resultados da pesquisa mostram a aplicabilidade do algoritmo de proteção, mesmo nas condições mais adversas, como na ocorrência da saturação dos transformadores de corrente.This work is based on the development and improvement of a methodology to differential protection of power transformer. The proposed methodology evaluates transient events that difficult the correct operation of differential relays applied to transformer protection. The study establishes contributions to the state of the art related to differential current analysis generated by internal and external faults and transient disturbance. The conception of the proposed methodology was based on the spectral energies variation generated by each event and calculated through the detail coefficient of Discrete Wavelet Transform. The proposed methodology was developed in MATLAB® environment and tested through several simulations performed with the ATP/EMTP software (Alternative Transients Program / Electromagnetic Transients Program). The results of the research show the applicability of the protection algorithms, even in adverse conditions, such as saturation of current transformers.
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Segatto, Ênio Carlos. "Relé diferencial para transformadores de potência utilizando ferramentas inteligentes." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-19022016-144637/.
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Este trabalho apresenta a proposta de um sistema completo de proteção diferencial de transformadores de potência, aplicando-se as técnicas de Redes Neurais Artificiais (RNAs). O esquema proposto busca a classificação do sistema de proteção como um problema de reconhecimento e reconstrução de padrões, representando um método alternativo aos algoritmos convencionais. Vários fatores como, por exemplo, as situações de energização do transformador e a saturação dos transformadores de corrente, podem causar uma má operação do dispositivo de proteção. Com o objetivo de melhoramento na proteção digital de transformadores de potência, desenvolveu-se um sistema de proteção diferencial, incluindo dispositivos com base em RNAs, em substituição à filtragem harmônica de sinais existente no algoritmo convencional. Em complementação, esquemas de reconstrução das ondas distorcidas provenientes da saturação dos TCs são também propostos e adicionados ao algoritmo final de proteção, sendo esses comparados ao algoritmo convencional de proteção diferencial de transformadores. Com a referida adição de ferramentas de inteligência artificial a um algoritmo completo de proteção diferencial de transformadores, obteve-se uma solução bastante precisa e eficiente, capaz de responder em um tempo reduzido, se comparada aos métodos convencionais.This work proposes a complete differential protection system for power transformers, applying the Artificial Neural Network (ANN) theory. The proposed approach treat the classification of the protection system as a problem of pattern recognition and as an alternative method to the conventional algorithms. Several factors such as, for example, transformer energization and CT saturation can cause an inadequate operation of the protection relay. With the objective of improving the power transformer digital protection, a complete protection system was developed, including an ANN-based device in substitution to harmonic filters, in use in the conventional algorithm. Some approaches concerning the reconstruction of the distorted signals caused by the CTs saturation are also proposed. These routines are added to the final protection algorithm and they are compared to the conventional algorithm for power transformer protection. With the use of artificial intelligence tools in a complete power transformer protection algorithm, one intends to obtain a very precise, fast and efficient solution, if compared to the conventional methods.
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Bernardes, Alexandre Paciencia. "Um esquema completo de proteção diferencial de transformadores para testes em um relé digital." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-16072006-122259/.
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Este trabalho apresenta um procedimento completo de simulação da proteção digital diferencial aplicada a transformadores de potência, visando o emprego deste à avaliação do comportamento de relés comercialmente disponíveis. Foi escolhido o software ATP (Alternative Transients Program) como ferramenta para a simulação de distintas situações sobre um sistema diferencial de proteção aplicado a um transformador de 25 MVA. Dentre as ocorrências evidenciadas, destacam-se: situações de faltas internas, faltas externas, situações de energização e energização com falta interna do transformador, condição de sobreexcitação e de saturação de TC (Transformador de Corrente). Cabe comentar que das simulações a real caracterização sobre o relé em teste, fez-se necessário todo um pré-processamento e análise da informação que será convenientemente abordada e justificada no trabalho apresentado, denotando-se um procedimento comum de teste a ser adotado a esta filosofia de proteção. A metodologia e esquema prático adotado trazem uma contribuição importante para a análise laboratorial de modelagens e simulações aplicadas a relés de proteção presentes no mercado e contribui de maneira substancial para os estudos teóricos de possíveis soluções para limitações eventualmente encontradasThis dissertation presents a complete procedure of simulation of digital differential protection applied to power transformers, focusing on its use to evaluate of the behavior of commercially available relays. Software ATP (Alternative Transients Program) was chosen as a tool for the simulation of distinct situations in a differential protection system applied to a 25 MVA three-phase transformer. Amongst the evidenced occurrences internal and external fault conditions, energization with or without internal fault of a three-phase transformer, overexcitation and CT (Current Transformer) saturation conditions were distinguished. It should be mentioned that from simulations to the characterization the real situations on the relay in test, a pre-processing and analysis of the information were necessary, and will be justified in the present study, denoting a common test procedure to be adopted to this philosophy of protection
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Jorge, David Calhau. "Transformadas wavelet aplicadas à proteção diferencial de transformadores de potência." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-18022016-093145/.
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Transformadores de potência são dispositivos que requerem atenção especial devido a sua grande importância ao sistema elétrico de potência no qual ele está conectado. Geralmente relés diferenciais são utilizados como proteção primária em transformadores de potência. Nestes relés, a corrente diferencial é comparada com um nível de ajuste e caso ocorra uma falta interna, o transformador deverá ser desconectado do restante do sistema. Entretanto, a simples detecção da presença de uma corrente diferencial não é suficiente para distinguir faltas internas de outras situações que também podem produzir tal corrente. Tais situações surgem durante a energização dos transformadores, devido a saturação dos transformadores de corrente, entre outras, as quais podem resultar em uma incorreta atuação da proteção. Uma rápida e correta discriminação entre faltas internas e outras situações é um dos desafios da moderna proteção de transformadores de potência. A respeito da identificação de faltas internas ou situações de energização, além da mencionada lógica diferencial é acrescentado uma subrotina baseada na restrição de harmônicas. Neste método, a corrente de energização é reconhecida através da presença de uma segunda harmônica obtida por filtros de Fourier. No entanto, o método de filtragem pode algumas vezes retardar a operação da proteção. Além disto, uma componente de segunda harmônica pode também estar presente durante uma falta interna. Este trabalho propõe a utilização da transformada Wavelet - uma poderosa ferramenta matemática - empregada como um meio rápido e eficiente de analisar as formas de onda de transformadores de potência e como uma alternativa a tradicional transformada de Fourier. Os sinais das correntes diferenciais são processados pelas transformadas discretas Wavelet, visando obter uma discriminação entre ambas situações (energização e falta). Um nível de limiar é utilizado após a decomposição Wavelet do sinal para discriminar entre as situações descritas. A janela de dados utilizada para este propósito pode ser variada. Para testar o algoritmo proposto, as simulações de energização e falta foram implementadas, utilizando o programa ATP (\"Alternative Transient Program\"). Em situações onde a janela de dados é reduzida para 1/4 de ciclo o critério de discriminação pode ser otimizado utilizando a transformada discreta de Wavelet auxiliada com técnicas de reconhecimento de padrões. Este trabalho apresenta a utilização de redes neurais artificiais para tal finalidade como exemplo. Resultados encorajadores são apresentados sobre a capacidade de discriminação para as situações descritas assim como a rapidez de resposta quando comparados aos métodos tradicionais.Power transformers are devices that require special maintenance and care due to their importance to the electrical system to which they are connected. Generally, differential relays are used for the primary protection of large transformers. In such relays, differential currents are compared to a threshold and in the case of an internal fault, the transformer should be disconnected from the rest of the system. However, a simple detection of a differential current is not sufficient to distinguish internal faults from other situations that also produce such a current. Some of these situations appear during transformer energization (inrush currents), CT (current transformer) saturation, among others, which can result in an incorrect trip. A correct and fast distinction of internal faults from the other situations mentioned is one of the challenges for modern protection of power transformers. Concerning the identification of internal faults as opposed to inrush currents, the approach tarditionally used is the aforementioned differential logic together with harmonic restraint. In this method, transformer inrush current due to energization is recognized on the basis of second harmonic components obtained by Fourier filters. However, the filtering method can sometimes delay the protection process. In addition to this, a second harmonic component can also be present during internal faults. This work proposes Wavelet transform - a powerful mathematical tool - employed as a fast and effective means of analyzing waveforms from power transformers, as an alternative to the traditional Fourier transform. The differential signals are processed by discrete Wavelet transform to obtain the discrimination between both situations (inrush and fault). A threshold level is utilized after the Wavelet decomposition to discriminate the situations describeb. The time window used for such purpose can be varied. In order to test proposed algorithm, simulations of fault and inrush currents in a power transformer were implemented using ATP ( \"Alternative Transient Program\") software. When the time window is reduced to only 1/4 of the cycle the discrimination criteria should be optimized using a pattern recognition technique to aid the Discrete Wavelet transform. This study shows as a sample for this purpose the use of artificial neural networks. Very encouraging results are presented concerning the capacity of discrimination of the described situations as well as the speed of response when compared to the traditional method.
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Silva, Rogério Cesar Serapião. "Projeto diferencial de geradores síncronos: o uso de redes neurais artificiais para identificação e correção da saturação dos transformadores de corrente." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-16042012-155039/.
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Este trabalho tem como objetivo apresentar um algoritmo de proteção diferencial de geradores baseado em Redes Neurais Artificiais (RNAs), que seja robusto e confiável em situações onde os algoritmos padrões podem apresentar dificuldades, como no caso, da saturação de TCs. O algoritmo desenvolvido é constituído por dois módulos principais: a) um módulo de detecção da saturação dos transformadores de corrente (TCs) empregados na proteção diferencial de geradores e; b) um módulo de correção das formas de onda distorcidas devido à saturação dos TCs. Os módulos utilizam RNAs para detectar e corrigir situações onde haja saturação dos TCs, a fim de evitar a má operação da proteção diferencial. O algoritmo foi desenvolvido em ambiente Matlab e validado com base nos dados da modelagem e simulações de um sistema elétrico utilizando o software Alternative Transients Program (ATP).This work has as objective to present an algorithm for differential protection of generators based on Artificial Neural Networks (ANN), which is robust and reliable in situations where standard algorithms fail, as in the case of Current Transformer (CT) saturation. The algorithm developed consists of two main modules: a) a module to detect saturation of CTs used in differential protection of generators and; b) module to correct distorted waveforms due to CT saturation. The modules use ANNs to detect and correct situations where there is saturation of CTs in order to avoid misoperation of the differential protection. The algorithm was developed using Matlab software and validated based on data modeling and simulations of a power system using the Alternative Transients Program (ATP) software.
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Igarashi, Gilberto. "Contribuições para a implementação de um barramento de processo segundo a norma IEC 61850-9." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-08072016-152036/.
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Desde seu lançamento, em 2002, a Norma IEC 61850 vem evoluindo para se tornar o padrão adotado nos Sistemas de Automação de Subestações. Dentre seus vários aspectos, destacam- se os serviços de tempo real, que permitem a implementação de funções de automação e de proteção dentro da subestação através da troca de mensagens específicas entre Dispositivos Eletrônicos Inteligentes através de um barramento digital de rede de dados. O objetivo central deste trabalho é explorar algumas das questões que envolvem a implementação de uma classe de serviços de tempo real: a transmissão de valores amostrados através de Serviços SMV, definidos pela Norma IEC 61850-9. Primeiramente, apresenta-se um breve resumo das principais características da Norma IEC 61850 que possibilitam o atendimento dos três requisitos por ela estabelecidos como base: a interoperabilidade entre dispositivos de diferentes fabricantes, a versatilidade na configuração e reconfiguração do Sistema de Automação da Subestação, e a possibilidade de implementação de novas tecnologias. Em seguida, explora-se com maior profundidade todos os aspectos relevantes à implementação dos Serviços SMV. Devido à complexidade deste assunto, o autor propõe abordá-lo sob a ótica de cinco tópicos interdependentes: variações da Norma IEC 61850-9, confiabilidade do barramento de processo, sincronismo de tempo, análise da qualidade da medição e segurança cibernética. Com base nos resultados apresentados neste estudo, propõem-se duas plataformas, um protótipo de Transformador de Potencial Óptico e um protótipo de Relé de Proteção Diferencial para transformadores de potência, com o objetivo de explorar alguns dos aspectos pertinentes à implementação de um barramento de processo de acordo com a Norma IEC 61850-9. Também foram realizados testes de geração e transmissão de mensagens contendo valores de amostras de tensão/corrente do sistema elétrico (denominadas de SV Messages) com a finalidade de implementá-las de fato e avaliar as ferramentas de mercado disponíveis. Por fim foi proposto um modelo para a simulação do sistema de potência em conjunto com a rede de comunicação utilizando o programa Matlab/Simulink. O autor espera que este trabalho contribua para esclarecer os vários conceitos envolvidos na implementação do barramento de processo definido pela Norma IEC 61850-9, auxiliando na pesquisa e no desenvolvimento de novas ferramentas e dispositivos, e no aprimoramento da Norma IEC 61850.Since its introduction, in 2002, the IEC 61850 Standard has been evolved to become the standard adopted in Substation Automation Systems. Among its various aspects it can be highlighted the real-time services, which allows the implementation of automation and protection functions within the substation by exchanging specific messages between Intelligent Electronic Devices via a digital data bus network. The main objective of this text is to explore some issues about the implementation of one class of real-time services: the transmission of sampled values through SMV Services, defined by IEC 61850-9 Standard. First, it is presented a brief summary of the main features of IEC 61850 Standard which allows it to meet the three main requirements on this standard: interoperability between devices from different manufacturers, versatility in configuration and reconfiguration of Substation Automation System, and possibility of implementation of new technologies. Next, it is explored, with more details, all aspects involved in the implementation of SMV Services. Due to the complexity of this subject, the author proposes approaches it from the perspective of five interdependent topics: variations of IEC 61850-9 Standard, process bus reliability, time synchronism, analysis of measurement quality, and cyber security. Based on results presented two platforms are proposed, an Optical Voltage Transformer prototype and a Differential Protection Relay prototype for power transformers, in order to explore some of aspects related to the implementation of a process bus according to IEC 61850-9 Standard. It was executed also some tests of generation and transmission of messages containing samples values of voltage/current from power system (referred as SV Messages) in order to implement them in fact, and to evaluate available market tools. At the end it is propoused a model for simulation of power system and network communication using Matlab/Simulink software. The author hopes this work may contribute to clarify the various concepts involved in the implementation of a process bus according to IEC 61850-9 Standard, aiding in research and development of new tools and devices, and improvement of IEC 61850 Standard.
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Barbosa, Daniel. "Sistema híbrido inteligente para o monitoramento e proteção de transformadores de potência." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-25102010-092314/.
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Este trabalho apresenta um conjunto de métodos para a proteção e o monitoramento de transformadores de potência baseado em sistemas inteligentes e na aplicação das transformadas de Clarke e Wavelet. A abordagem inteligente utilizada permite analisar a condição operativa dos transformadores de potência e detectar a ocorrência de defeito interno, distinguindo-a de outras situações de operação, como, a energização, a energização solidária, a saturação dos transformadores de corrente e a sobreexcitação. As tomadas de decisão das técnicas desenvolvidas são realizadas pela lógica fuzzy após o pré-processamento dos sinais de entrada por meio de diversos métodos, os quais variam de acordo com o algoritmo que esta sendo executado. Os algoritmos propostos foram testados por meio de simulações realizadas através do software Alternative Transients Program (ATP). É importante salientar que nas simulações do ATP foram modelados diversos equipamentos que constituem o sistema elétrico de potência, incluindo um gerador síncrono com regulação de velocidade, linhas de transmissão com variação em frequência, transformadores de potência com suas respectivas curvas de saturação, transformadores de potencial e de corrente. Estas modelagens tiveram por objetivo gerar dados das distintas situações de operação para a verificação e análise da metodologia proposta. Os resultados da pesquisa mostram a aplicabilidade dos algoritmos propostos na proteção e no monitoramento dos transformadores de potência, mesmo nas condições mais adversas, como na ocorrência da saturação dos transformadores de corrente, uma vez que os sinais de entrada distorcidos pela saturação são corrigidos por uma rede neural artificial. Os resultados apresentados comparam as respostas obtidas pelas técnicas propostas em relação às saídas de um relé comercial, habilitado à proteção diferencial percentual.This work presents a set of methods for protecting and monitoring power transformers based on intelligent systems and the application of Clarke and Wavelet transforms. The intelligent approach allowed us to analyze the operating condition of power transformers and it discriminates between an internal fault and different operating conditions, as energization, sympathetic inrush, saturation of current transformers and overexcitation. Decision making is performed by fuzzy logic after the preprocessing of the input signals through various methods, varying according to which algorithm is running. It is important to point out that in the simulations using ATP many different power system equipment had been modeled, including a synchronous generator with speed regulation, transmission lines with variation in frequency, power transformers with their saturation curves, potential transformers and current transformers. The objective of these tests was to generate data for distinct situations for the verification and the analysis of the proposed methodologies. The results of the research show the applicability of the algorithms considered in protection and monitoring of power transformers, even in adverse conditions, such as saturation of current transformers, since the input signals are distorted by CT saturation corrected by artificial neural network. The results are compared to the ones presented by a commercial percentage differential relay.
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Hrycík, Tomáš. "Porovnání použití přístrojových transformátorů a senzorů v aplikacích s ochranou REF 542plus." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218429.
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The aim of this Master´s thesis is use of instrument transformers and sensors on field of industry protection. We will compare current and voltage transformers, current sensor – based on Rogowski coil, voltage sensor – based on voltage divider. By this measure devices, we can monitoring values of analog quantities in medium voltage switchgear. It is impossible to compare, measure and analyze without this measure devices. There is protection terminal REF542plus, which can compile this values. The REF542plus ability are measuring, monitoring, remote control and protection. First, we will discuss about theory of sensors and convential instrument transformers and analysis of analog signal. We will compare analog input channel on sensor´s analog module and transformer´s analog module. There are few differences between type of analog modules. For analog signal analysis are important frequency filters and Analog/ Digital Convertor (sigma-delta). We will describe functions and options of REF542plus. In practical part of this project, we will test protection functions of protection terminal. First, protection terminal will be connected to sensors. Second protection terminal will be connected to transformers. For testing we chose Earth-fault directional protection and differential protection. We will make only secondary tests. That´s mean, input analog quantities to REF542plus will be simulated by tester. In all we will verify quality of protection. We will focus on lower settings of protection and we will inject protection by low current. Objectives are testing of trip characteristics and measuring of trip time.
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Marques, Jeferson Prates. "Proteção de transformadores de potência eclassificação de transitórios elétricos por meio da transformada wavelet discreta." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/8549.
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This dissertation presents the development of an algorithm for classifying
electrical transients in power transformers for protection. Initially the main transient
involving power transformers were analyzed, with a special focus on the magnetizing
current that occur during energizing equipment, known as inrush currents. Among the
studied transient, current inrush are those that present greater difficulty in
identification and discrimination by the differential protection, due to its high peak
magnitude. In a second moment, was developed a test system implemented in ATP /
EMTP software for the simulation of different operating situations of the power
transformer, current data being obtained from TCs for analysis. After known the
problem and implement a test for acquisition system, we developed an algorithm
based on the last samples of the detail coefficients, called Details Signals, from the
decomposition of the data of differential phase current using the Discrete Wavelet
Transform. The methodology has the objective improve the system for protection of
the transformer, becoming one efficient alternative for the identification of transients.Esta dissertação apresenta o desenvolvimento de um algoritmo para classificação de transitórios elétricos em transformadores de potência, para fins de proteção. Inicialmente foram analisados os principais transitórios associados aos transformadores de potência, tendo um foco especial na corrente de magnetização que surge durante a energização do equipamento, conhecida como corrente de inrush. Dentre os transitórios estudados, as correntes de inrush são as que apresentam maior dificuldade de identificação e discriminação por parte da proteção diferencial, devido a sua alta magnitude de pico. Em um segundo momento, foi desenvolvido um sistema teste implementado no software ATP para a simulação das diversas situações de operação do transformador de potência, sendo obtidos dados de correntes a partir dos TCs para análise. Após conhecer o problema e implementar um sistema teste para a obtenção dos dados, desenvolveu-se um algoritmo baseado nas últimas amostras dos coeficientes de detalhes, chamada de Sinais de Detalhes, provenientes da decomposição dos dados de correntes diferenciais das fases por meio da Transformada Wavelet Discreta. A metodologia desenvolvida tem como objetivo melhorar o sistema de proteção do transformador, tornando-se uma alternativa eficiente para a identificação de transitórios.
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Komárek, Filip. "Návrh rekonstrukce stávající vstupní rozvodny a kabelové sítě 22 kV v areálu fakultní nemocnice." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377072.
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This master's thesis deals with the area hospital distribution networkand one of the hospital's entry substation. The first part of this master's thesis deals with the project of the new cable network, her gradual revival without any power outages at the collection points. Futher, in this thesis is project of temporary transformer station for supplying power during the reconstruction of the HV switchboard. Subsequently, in this thesis is project of the new HV switchboard in one of the entry substation. new HV switchgear and a new HV substation were projected. Futher, in this thesis is proposed compensation of the whole area, including the HV network.
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SOUZA, CLECIA de M. "Utilização da radiação ionizante na reciclagem de pneus inservíveis de automóvel e sua destinação ambiental adequada." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10613.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Chen, Chun-wen, and 陳俊文. "Applications of Current Transformer Jiles-Atherton Modeling for Differential Protection Studies." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/82600593705052843120.
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碩士逢甲大學
資訊電機工程碩士在職專班
94
This thesis simulation procedure of use the electromagnetic transient program （EMTP） analyze differential protect in bus structure of model. The direct current （DC） offset component of current will be produced when the fault occurs in power system. This Dc offset of current is flowing into a protective current transformer （CT）, it will cause the core of CT to saturate and produce a distorted secondary current because of too large Dc offset component, and core hysteresis results in a residual flux that also affects the CT transient behavior. It produces the factor which miss movements that all these may cause and protect the electric post differentially, and while protecting the electric post differentially and missing movements, will lead to the fact the steady problem of degree of the system happens, cause the serious perturbation. When more difficult to measure CT excitation current or magnetic field, when CT saturates. Utilize Jiles-Atherton （J-A） function model, it is magnetism not unshakable in one''s determination characteristic and outside circuit if coming, analyze intact simulation combining. use EMTP of the Correct simulation is analyzed Probe the main factor of mistake movements differentially protecting relay.
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Chen-Hong, Tsai, and 蔡正宏. "Special Application of Digtal Relay : Fault Location Identification for Underground Cable in Steel-Pipe and Differential Protection for Le-Blanc Transformer." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/91619241957329585794.
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Kwang-Chang, Lu, and 盧光常. "The Phasor Combination Differential Protection for Le-Blanc Transformers-." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/b2z56s.
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博士國立臺灣科技大學
電機工程技術研究所
86
The Le-Blanc transformer is a specially connected transformer that transforms a three-phase power system to a two-phase or two single-phase powersystems. It is the main transformer of electric railway in Taiwan to transform69 kV(three-phase) to 25 kV(single-phase) system. Owing to the specialwinding connection and different phase transformation, Le-Blanc transformerscannot use conventional differential protection directly. Therefore, theovercurrent protection became the main electrical protection of Le-Blanctransformers. The purpose of this research is to design a differential protectivescheme for Le-Blanc transformers. Three differential protective schemes forLe-Blanc transformers have been designed based on a current phasor combination method: (1) Three-relay protective scheme--Match the secondary current phasors of Le-Blanc connection to the primary current phasors. (2) Two-relay protective scheme--Match the primary current phasors to the secondary current phasors of Le-Blanc Connection. (3) One-relay protective scheme--Match the primary and secondary current phasors of Le-Blanc connection to the same phasor. Results of practical design examples using the parameters of a Le-Blanc transformer of Taiwan Railway Bureau(Tairail) are described in this thesis. The low mismatch sufficiently explains why the differential protection ofLe-Blanc transformers can be achieved by these schemes. In addition, laboratory test results also depict the feasibility of the proposed protectiveschemes.
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劉育志. "The Phasor Combination Differential Protection for Scott and V-V Transformers." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/81794834777955698425.
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碩士國立臺灣科技大學
電機工程系
87
The main protection for a general power transformer (over 10MVA) is normally achieved by a differential protection scheme. Due to different phase numbers in the two sides of a specially-connected transformer used in electrified railway systems, a traditional differential protection scheme for a general power transformer cannot be used. Presently, the over-current relay is used as the main protection and an over-voltage relay is the backup. The purpose of this thesis is to design a differential protective scheme for some specially-connection transformers which are the main transformers of the electric railway. Current phasor combination method is applied to it and the design procedure is the same as the differential protection of normal power transformers. The designs are applied to the Scott connection transformers used in Tokaido-Shinkansen and the V-V connection transformers used in TGV in France and ECML in Great Britain. Finally, a scaled down system is implemented in a laboratory to simulate the Scott connection and V-V connection transformers to assure that the protection function can reliably protect them against faults.
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Apostolo, Pedro Miguel Machado. "Fault diagnosis and protection of phase-shifting transformers." Master's thesis, 2014. http://hdl.handle.net/10316/40408.
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Tsou, Tsung Ling, and 鄒宗龍. "The Effect Analysis and Simulation Test of Harmonics on Differential Protection of Special Transformers." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/75702761655663144858.
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碩士中原大學
電機工程學系
88
All the of high speed railway systems around the world use single phase voltage to the trains. Because of the large variations of electric power when starting and breaking the trains, there arises a lot of harmonics in the system. The nonlinear load may cause a lot of harmonics, too. These affect the power quality and may misoperate the protection relays. The research aims at the effects of harmonic to the differential protecting special transformer. The CA type differential relay is used to protect the special transformer, and the Scott transformer is selected. Different combinations of harmonics are need for testing. A relationship between the tripping time of the differential relay and the harmonics quantity are found. We expect the results will be helpful and useful to the applications of differential relays to special transformer.
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Hsu, Hsiang-Peng, and 徐享鵬. "The Effect Analysis and Simulation Test of Harmonics on Differential Protection for Scott Transformers." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/cuuxw7.
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碩士中原大學
電機工程研究所
91
All of the High Speed Railway (HSR) systems around the world used single phase voltage to the trains, and adopted three-phase to two-phase special transformer to supply electric power. Due to the large variations of electric power when starting and braking the trains, there arises a lot of harmonics in the motor-driven system. And the nonlinear loads may cause a lot of harmonic, too. Scott transformer has a special wiring structure, it’s major purpose is to transfer a three-phase power source into a balance two-phase or two single phase power source for supplying special single plase loads. The research aims at the effects of harmonic to differential protecting relay of Scott transformer. The CA type differential relay is used to protect the Scott transformer. The instrument, ELGAR Smart Wave SW5250, is used to generate for the different waveforms this experiment. We hope the results can be a valuable reference for protection design for Scott transformer.
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Cao, Zhi-Hao, and 曹志豪. "The Influence of Differential Protective due to the Saturation Characteristic of Current Transformers." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/08487578808837127538.
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碩士逢甲大學
電機工程學系
89
The relay of power system often causes miss-action due to the saturation characteristic of current transformers so that it does damage in system equipment and has a tremendous effect on the protection and operation of power system. Therefore, this thesis explores the possible effects on the transient over-current phenomenon caused by the current transformer because it breaks down. To further understand the cause and effect of this phenomenon, this thesis intends to apply the describing function to nonlinear system in order to establish a model of current transformer saturation characteristics. In doing so, we can explore the possible influences that the saturation of the current transformer has on the differential protection of the power system。 This thesis utilizes the describing function before adopting the function of Transient Analysis of Control Systems （TACS）in Electromagnetic Transient Program（EMTP）to build up the model of current transformer saturation characteristic. This thesis also attests the accuracy of the model when the power system breaks down. It also builds up the phasor-combination differential protection. It investigates the influence of the current transformer saturation characteristic on differential protection by simulation. Keywords: Describing function, model of Current Transformer Saturation Characteristic, Differential Protection.
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"Implementation of Pilot Protection System for Large Scale Distribution System like The Future Renewable Electric Energy Distribution Management Project." Master's thesis, 2014. http://hdl.handle.net/2286/R.I.24940.
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abstract: A robust, fast and accurate protection system based on pilot protection concept was developed previously and a few alterations in that algorithm were made to make it faster and more reliable and then was applied to smart distribution grids to verify the results for it. The new 10 sample window method was adapted into the pilot protection program and its performance for the test bed system operation was tabulated. Following that the system comparison between the hardware results for the same algorithm and the simulation results were compared. The development of the dual slope percentage differential method, its comparison with the 10 sample average window pilot protection system and the effects of CT saturation on the pilot protection system are also shown in this thesis. The implementation of the 10 sample average window pilot protection system is done to multiple distribution grids like Green Hub v4.3, IEEE 34, LSSS loop and modified LSSS loop. Case studies of these multi-terminal model are presented, and the results are also shown in this thesis. The result obtained shows that the new algorithm for the previously proposed protection system successfully identifies fault on the test bed and the results for both hardware and software simulations match and the response time is approximately less than quarter of a cycle which is fast as compared to the present commercial protection system and satisfies the FREEDM system requirement.Dissertation/Thesis
M.S. Electrical Engineering 2014