Le transformateur de puissance est un équipement essentiel d’un réseau électrique et le plus coûteux dans les postes. Pour augmenter son degré de disponibilité et de fiabilité, il est nécessaire d’appliquer la manœuvre contrôlée afin de diminuer la saturation du noyau lors de l’enclenchement, et donc limiter les courants d’appel. Ces derniers sont asymétriques, d’amplitude élevée, et riches en harmoniques. Ils peuvent causer des effets indésirables comme le disfonctionnement des dispositifs de protections, l’endommagement mécanique des enroulements du transformateur et réduire en général la durée de vie et la qualité des systèmes. Une technique efficace pour réduire ces courants d’appel est de mettre sous tension le transformateur quand le flux dynamique généré par la source est égal à son flux rémanent. Un modèle simplifié du transformateur de puissance est adopté pour l’analyse des phénomènes physiques liés à l’application des manœuvres. Pour évaluer le degré de faisabilité de cette technique, des simulations sont effectuées en utilisant le simulateur de réseau EMTP. Les contraintes requises pour chacun des composants du système de manœuvre contrôlée comme les segments de ligne, les disjoncteurs sont étudiées en détail pour déterminer l’algorithme de calcul de l’instant optimal de manœuvres. Ensuite des tests de validation statistiques sont effectués afin d’évaluer les performances des différentes approches employées. Enfin une étude consacrée à la reconstitution du flux rémanent via un transformateur capacitif de tension (TCT) est menée pour appliquer l’algorithme de manœuvre contrôlée dans les postes en utilisant les équipements de mesure déjà existants. / Power transformers are vital equipment in electrical networks and are the most expensive ones in substations. In order to increase their availability and reliability, controlled switching must be applied for reducing cores saturation during its energization, called “inrush currents”. These inrush currents are asymmetrical, high-magnitude, harmonic-rich, and may cause many undesirable effects such as maloperation of protective relays and fuse, mechanical damage to the transformer winding and generally reduce the lifetime and quality of power systems. An efficient technique to reduce these inrush currents is to energize the transformer when the dynamic flux generated by the source is equal to its residual flux. A simplified model is adopted to analyze the physical phenomena related to the switching applications. In order to assess the feasibility of this technique, numerous simulations have been performed using EMTP simulator. The critical requirements for each component of the controlled switching system such as pieces of line, circuit breakers have been studied in detail in order to determine the best switching instant calculation algorithm. Then statistical validation tests have been conducted to evaluate the performances of its different approaches. Finally a study dedicated to the reconstitution of residual flux using a capacitive voltage transformer (CVT) has been carried on in order to apply the controlled switching algorithm in substations using their existing measurement equipments.

Nesta pesquisa, apresentam-se os principais eventos relacionados com a proteção de transformadores e sua correlação com os distúrbios de qualidade da energia elétrica (QEE). Neste sentido, foi desenvolvido um algoritmo que utiliza a transformada Wavelet (TW) e a lógica Fuzzy (LF) para classificar os eventos transitórios associados à proteção de transformadores. Estes eventos foram observados em um sistema elétrico de potência (SEP) simulado com a utilização do software Alternative Transients Program (ATP). Importa ressaltar que o sistema modelado apresenta transformadores ligados em paralelo, possibilitando o estudo de eventos decorrentes desta situação, como a energização solidária (Sympathetic Inrush). Por este SEP, modelado sobre parâmetros reais, foram simuladas várias situações transitórias, que provocam o aparecimento de correntes diferenciais, sendo estas direcionadas para análise do algoritmo desenvolvido. Afirma-se que, nos testes realizados, o algoritmo proposto apresentou um desempenho satisfatório perante as mais variadas situações a que foi submetido, identificando as causas das correntes diferenciais, sejam proporcionadas por defeitos ou por outras condições de operação aplicadas. / In this research, the main events related to the transformer protection and its correlation with the power quality disturbances (PQ) are presented. In this context, an algorithm based on Wavelet transform (WT) and Fuzzy logic (FL) was developed to classify the transient events associated with the transformer protection. These events were observed in an electrical power system (EPS) simulated using the Alternative Transients Program (ATP) software. It should be emphasized that the modeled system presents transformers connected in parallel, allowing the study of events of this situation, such as sympathetic inrush. For the simulated EPS, modeled based on real parameters, various transients situationswere simulated, causing the appearance of differentials currents which were directed to the analysis. The proposed algorithm showed a satisfactory performance tomany situations, identifying the causes of the differentials currents, either provided by faults or other operation conditions.

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.

Lors de la réalimentation des auxiliaires d'une tranche nucléaire ou hydraulique, l'étape la plus à risque est la remise sous tension brusque du transformateur à cause des surtensions et courants d'appels générés. Ces phénomènes transitoires engendrent des effets très indésirables autant pour le réseau comme pour le transformateur (efforts électrodynamiques sous les bobinages, vibration du circuit magnétique, bruit et vieillissement prématuré du transformateur.) Le but de ces travaux de thèse est de proposer de nouvelles méthodologies permettant d'évaluer les paramètres mal connus (les valeurs des flux rémanents présents dans le circuit magnétique du transformateur avant sa mise sous tension). Face aux problèmes actuelles pour l'estimer (méthode non directe, dérive, imprécision de la mesure de la tension, etc.), deux nouvelles méthodes basées sur la magnétisation préalable du circuit magnétique (méthode de prefluxing) et sur la mesure des flux de fuites du circuit magnétique (méthode de mesure directe de flux par mesure de l’induction magnétique) sont proposées. / During the re-energization of the auxiliaries of a nuclear or hydraulic power plant, the most dangerous step is the re-energization of the power transformer, because of the temporary overvoltage and inrush currents. These transients phenomenon causes undesirable effects for both network and for the power transformer (electrodynamic forces over the windings, the magnetic circuit’s vibration, noise and the premature aging of the transformer). The goal of these thesis is to suggest new methodologies allowing us to evaluate unknown parameters (the residual flux’s values in the magnetic circuit before transformer’s energization). According to the latest problems in order to evaluate it (no direct method, derivation, voltage measurement error, etc) two new methods based on the previous magnetization of the magnetic circuit (prefluxing method) and on the leakage flux measurement of the magnetic circuit (direct measurement of the flux by measuring the magnetic induction method) are proposed.

This thesis proposes innovative methods to extract information embedded in the frequency and time domain response of the transformer winding, and utilizes them to suggest solutions to a few tasks that have until now been thought difficult, if not impossible, to resolve. Pursuing this philosophy originated from the basic under- standing that the response of any physical system (behaving largely as a linear time invariant system) has embedded information that characterizes it completely. So, the prerequisite is to evolve ways to extract this information from measured responses. Once that is done, a variety of interesting applications can be envisaged. The two applications considered in this thesis are- •Investigate indirect measurement of the series capacitance of a transformer winding using the measured frequency or time domain response •Explore the possibility of increasing the physical resolution of the ladder network used to model a fully interleaved-disk winding In the former application, since direct measurement of series capacitance is impossible, alternatives based on indirect measurement were also not attempted. Similarly, in the latter application, the upper limit is known to be fixed by the number of distinctly observable peaks in the magnitude frequency response, so the question of increasing this limit was also never explored. Solutions to these tasks are proposed after a systematic analysis of frequency/time domain responses of a winding, initially modeled as a lumped parameter ladder network, to extract correlations that exist between them and winding parameters, and finally examine how these relations can be exploited together with the measured responses. Each of the five chapters is dedicated to describe the solution to one task. In each chapter, analytical formulation is presented first, followed by experimental results. Good agreement with the predicted results demonstrates its practicability. In final summary, indirect measurement of the series capacitance of a winding and en- hancing physical resolution of a ladder network model to represent a fully interleaved- disk winding was successfully demonstrated and they are the main contributions of this thesis.

This assignment is based on the tolerance problems that occur with the radial dimensions or RR-dimensions for the windings. The purpose is to identify the various parameters that affect said RR-dimensions and where these parameters originate from to be able to assure quality of the winding process. The RR-dimension has a tolerance of + 2,2 and - 1,1 mm, but it is only the positive tolerance that cause problems. The case study is based on a mixture of quantitative and qualitative methods. Quantitative data collections of dimensions for leaders and how the RR-measurement are affected by them, analysis of tolerances and how well they are adapted for their purpose. Qualitative observations, experiments and semi-structured interviews have also been conducted to gain a deeper understanding of the problem. The results show that tolerance problems originate from several different factors. The first factor is the debatable tolerance setting on some conductors, mainly the thin CTC conductors that do not have a high radial dimension. These conductors have tolerances that do not fill a purpose because it does not ensure the quality for the winding. The conductors need a tighter tolerance spectrum for the positive direction to be fully functional. The air gap that can occur between the conductors is also a cause of error. This stems from the fact that it is not possible to achieve a sufficiently high force when tensioning the disc. This can also occur from the uneven surface of the CTC-conductor that can create gaps. Another cause of error that affects the dimension is the number of turns for a disc. When a disc is wound with a high number of turns it will lead tothat the influencing factors have a higher amount of turns to effect on. This means that a small increase of the conductor's nominal dimension or small air gaps has a large impact on the overall RR-dimension. / För att kvalitetssäkra transformator- och reaktorlindningarna hos företaget Hitachi ABB skade utsatta toleranserna för varje lindning uppfyllas för att kunna fortsätta vidare i produktionslinan. Arbetet är grundat utifrån de förekommande variationerna hos lindningarnas mått i radiell riktning (RR-mått. Arbetets syfte är att undersöka Hitachi ABB:s lindningsproduktion för att finna de faktorer som ger upphov till måttvariationer hos RRmåttet. De identifierade faktorerna ska användas för att kvalitetssäkra företagets lindningsprocess. Färdigställt arbete ska användas som grund för företagets fortsatta arbetekring kvalitetssäkring. RR-måttet har en tolerans på + 2,2 och – 1,1 mm, däremot är detendast de variationer i positivt led där problem uppstår. Vid ett för högt mått genomförs enutredning för att se över om lindningen kan brukas ändå eller utifall de för höga måttet i radiell riktning påverkar prestandan samt montering. Arbetet är en fallstudie utfört med en blandning av kvantitativa och kvalitativa metoder. Denkvantitativa datainsamlingens syfte är att undersöka ledares mått i lindningar för att se hur RR-måttet påverkas måttsättning och varvantal. Den kvantitativa datainsamlingen genomför också analyser av toleranser och hur väl anpassade de är för sitt syfte. Kvalitativa observationer, experiment och halvstrukturerade interjuver har genomförts för att skapa en djupare förståelse kring problemet.Resultatet visar att de variationer som uppstår hos RR-måttet påverkas av flera olika faktorer.Variationer hos RR-måttet uppstår främst för lindningar där en CTC-ledare används. En påverkande faktor är toleransvidden för ledarna, främst för de tunna CTC-ledarna. Ledarna lindas runt varandra där ledarens mått staplas på varandra för att bilda ett RR-mått. För de tunna CTC-ledarna bör en mindre toleransvidd användas, mer specifikt en lägre positiv tolerans likt de platta ledarna för att kunna kvalitetssäkra lindningen. En annan påverkandefaktor är de luftspalter som uppstår mellan ledarna. Luftspalter härstammar ifrån att det integår att uppnå tillräckligt hög kraft vid spänning av en skiva alternativt från CTC-ledarens knöliga yta. Utöver dessa två faktorer har antalet lindade varv för en skiva en påverkan förtoleransstapling. Fler varv resulterar i att små måttavvikelser för ledare påverkar det totala måttet, vilket innebär att de luftspalter som kan uppstå blir fler när antalet varv ökar.

This diploma thesis discusses two major topics. The first one is the control size of the voltage in LV networks in regard to the increase in distributed generation concered to renewable energy sources. The study contains a review focused on the current state of low voltagegrid followed by a proposal for the solution of the oncoming state. The solution is identified as a deploying OLTC distribution transformer. In the case of more complex topology is deployed a series voltage transformer. Both methods are part of the Smart Grid. The thesis also analyzes the issue of the data measurement and data transmission. The second part of the thesis consists of the description of selected control strategies and their simulations. The design of individual system elements in the PSCAD is described. From these elements, a test network was constructed and tested the individual simulation scenarios.

This thesis deals with the description, analysis, calculation, production and testing of current instrument transformer. It is a measuring current transformer in one turn primary winding with 2500/1 A transfer. This project includes theory, analysis, numerical calculation, thermal simulation and partial type test of the measuring current transformer. This transformer is developing in cooperation with KPB Intra s.r.o. KPB Intra is engaged in the development and production of instrument transformers.

This thesis deals with design of a DC/DC converter for powering the oscilloscope. The main parameters for selecting a suitable inverter are: galvanic isolation of input and output parts of the inverter and low parasitic capacitance of galvanic isolation. The required power of the inverter is 100 W and the output voltage is 325 V. The introduction briefly explains why the DC/DC converter with transformer will be used. The first part of the work deals with the selection of a suitable types of DC/DC converter with transformer for powering the oscilloscope. The next part is devoted to designing of the power parts of resonant converter and single acting flyback converter. This is followed by a complete design of a single-acting flyback converter, including the realization and measurement of the time courses of important quantities.

The fist part of this work is dealt with the construction of the mathematical models of voltage and current transformers. There are created and simulated models of voltage and current transformer with the nonlinear magnetization characteristics. The second part of this work is dealt with equivalent circuit of the induction motor in the form of Gamma-circuit. The speed-torque characteristic and the dependence of stator current on the slip are calculated from this equivalent circuit. The third part of this work is dealt with electromagnetic design of the alternating current machines by the help of a classic way and a new way.