The diploma thesis provides an insight into the remote control and disconnection of DSO supply points phenomenon. The remote or local disconnection/connection of supply point is allowed by the breaker function. The automatic disconnection of supply point is enabled by the limiter function. Due to the anticipated implementation of smart meters in the Czech Republic in the future, this work contains the comprehensive description of breaker/limiter function with proposed possibilities of use in the Czech Republic. The thesis deals with the current breaker/limiter function use in the Czech Republic and in other countries. It introduces the smart meter installation in pilot projects to analyze the breaker/limiter function use in other countries. The thesis is focused on the technical solution of breaker/limiter. Moreover, it describes the ways of connecting the breaker, settting the limiter, connecting/disconnecting a supply point and breaker operation. Further, the thesis introduces the ways of activating the breaker by a customer and defines in which cases it is possible to limit and interrupt the electricity supply in the Czech Republic currently. The main aim of thesis is to describe the specific possibilities of breaker/limiter function use in the Czech Republic. With regard to the function use in other countries and the limiting or interrupting the electricity supply by DSO according to energy law, the possibilities of use are proposed. Each possibility of use is analyzed when implementing the breaker function or the breaker/limiter function. The benefits are defined for a DSO and for a customer. The proposed uses are evaluated in terms of applicability and valid legislation in the Czech Republic. The result of this work is the summary of information about breaker/limiter function which is one of the new features in the implementation of smart metering. The function installation and the implementation of possibilities described in the thesis depends on the DSO decision.

Finite volume methods employing second-order gradient reconstruction schemes are often utilized to computationally solve the governing equations of fluid mechanics and transport. These schemes, while not as dissipative as first-order schemes, frequently produce oscillatory solutions in regions of discontinuities and/or unsatisfactory levels of dissipation in smooth regions of the variable field. Limiters are often employed to reduce the inherent variable over- and under-shoot; however, they can significantly increase the numerical dissipation of a solution, eroding a scheme’s performance in smooth regions. A novel gradient reconstruction scheme, which shows significant improvement over traditional second-order schemes, is presented in this work. Two implementations of this Optimization-based Gradient REconstruction (OGRE) scheme are examined: minimizing an objective function based on the mismatch between local reconstructions at midpoints or selected quadrature points between cell stencil neighbors. Regardless of the implementation employed, the resulting gradient calculation is a compact, implicit method that can be used with unstructured meshes by employing an arbitrary computational stencil. An adjustable weighting parameter is included in the objective function that allows the scheme to be tuned towards either greater accuracy or greater stability. To address over- and undershoot of the variable field near discontinuities, non-local, non-monotonic (NLNM) and local, non-monotonic (LNM) limiters have also been developed, which operate by enforcing cell minima and maxima on dependent variable values projected to cell faces. The former determines minimum and maximum values for a cell through recursive reference to the minimum and maximum values of its upwind neighbors. The latter determines these bounding values through examination of the extrema of values of the dependent variable projected from the face-neighbor cell into the original cell. Steady state test cases on structured and unstructured grids are presented, exhibiting the low-dissipative nature of the scheme. Results are primarily compared to those produced by existing limited and unlimited second-order upwind (SOU) and first-order upwind (FOU). Solution accuracy, convergence rate and computational costs are examined.

For effective operation of microgrid systems (MGSs), it is important to understand the major types of power grid failures and how to deal with them. Detecting the fault, locating it, and isolating the faulty line are important to avoid damaging components and interrupting the service for customers. This will also improve the reliability and protection level of the system during fault conditions. Among the most successful protection methods to limit fault currents in power systems is the fault current limiter (FCL). The FCL improves the reliability of the system, voltage stability, and the fault current reduction. However, limited researches consider its applications inMGSs. The location and impedance size of the FCL play a major role in limiting fault currents in the system. Several studies concluded that installing FCLs near all generators, transformers, or loads in the system enhanced the performance of the system during fault conditions. However, increasing the number of FCLs in the system leads to an increase in cost. This dissertation proposes several effective approaches to specify the optimal locations and impedance values of the required number of installed FCLs in a grid-connected MGS. These FCLs improve the reliability and the protection level of the system by limiting fault currents during fault conditions. The goal is to reduce the required number of installed FCLs in the system. These installed FCLs must be able to reduce fault currents under the interrupting ratings of circuit breakers in the system. This goal will lead to lower the cost of installed protection devices in the system. In order to achieve this goal, this dissertation presents a novel fault management approach, sensitivity analysis, and an optimization model to find the optimal solutions. The study of this dissertation is meant to be used during the planning stage of power distribution system design. The results of this dissertation prove the robustness of the proposed approaches. This enhances the system’s performance while minimizing the required number of installed FCLs. Their sizes limit fault currents within safe ranges. Thus, the FCL significantly improves the reliability and protection scheme of the grid-connected MGS.

No description available.

Dans ce travail de thèse, nous souhaitons exploiter les interactions non-linéaires entre le signal micro-onde de forte puissance à émettre et des micro-décharges plasmas intégrés dans les circuits ou antennes micro-ondes de l’émetteur (e.g., émetteur de télécommunications, RADAR, ...) pour obtenir sa reconfigurabilité. Une telle problématique adresse un ensemble de compétences à l’interface entre la physique des plasmas et les micro-ondes. Elle concerne aussi bien des problématiques amont que des considérations d’ingénierie. Le travail à réaliser au cours de ce projet doit permettre de progresser en deux tâches de recherche qui structureront les activités de la thèse. En premier lieu, la caractérisation des micro-décharges plasmas sera effectuée puis il sera possible d'identifier et de développer des dispositifs micro-ondes reconfigurables. / In this project, the non-linear interactions between the high-power microwave signal and micro-discharges plasmas integrated in the microwave circuits or antennas of the transmitter (for example,Telecommunication transmitter, RADAR, ...) will be exploited to obtain its reconfigurability. Such a problem addresses a set of competences at the interface between plasma physics and microwaves. It concerns both upstream and engineering considerations. The work to be carried out during this project should make it possible to progress in two research tasks that will structure the activities of the thesis. First, the characterization of microdischarge plasmas will be perform then it will possible to identify and develop reconfigurable microwave devices.

Limitadores de corrente supercondutores resistivos (LCSR) são dispositivos com características elétricas próximas ao ideal quando ocorre a transição do estado supercondutor para o estado normal, limitando a corrente de falta através da inserção rápida de uma resistência na rede. A viabilidade técnica e econômica destes limitadores aumentou após o desenvolvimento dos supercondutores de alta temperatura crítica HTS. A primeira geração de fitas HTS (BSCCO) consiste em multifilamentos de material supercondutor embutidos em uma matriz de prata. A densidade de corrente crítica típica é de aproximadamente 140 A/mm2. Contudo, a resistência alcançada pelo LCSR quando atinge o estado normal não é suficiente para limitar a corrente de falta, sendo necessários longos comprimentos de fitas (~5 km) para que a corrente seja limitada. O recente desenvolvimento de fitas supercondutoras de YBCO com filmes finos texturizados e com substrato de alta resistividade superou o desempenho das fitas de BSCCO para esta aplicação. Com uma densidade de corrente crítica de 136 A/mm2, as fitas de YBCO são bem conhecidas pelo seu alto valor de índice n (aproximadamente 30), rápida resposta de transição após falta e alta resistência elétrica no estado normal. Neste trabalho foram analisados o comportamento elétrico e magnético das fitas de BSCCO e YBCO (em amostras curtas de 0,2 m) utilizando diferentes técnicas de caracterização das propriedades das fitas HTS. A partir destes resultados, medidas com pulsos de corrente DC e AC com intensidades de 3 a 7 vezes a corrente crítica do sistema (I=720 A a 1700 A) com duração de 1 a 5 ciclos da rede em 60 Hz (16 a 80 ms) foram realizados de forma a obter as características do tempo de recuperação em um elemento contendo 4 fitas em paralelo (0,4 m). Os resultados permitiram o projeto, construção e medidas em corrente AC de um protótipo LCSR (Ipico = 2 kA) contendo 16 elementos sob condições normais de operação da rede (220 V - 60 Hz). / Resistive Superconducting fault current limiter (SFCL) are devices with electrical behavior near the ideal when it changes its state from the superconducting to the normal state, limiting the fault current by the insertion of a fast transition resistance in the grid. The technical and economical feasibility of these limiters arose after the development of the high critical temperature superconductors HTS. First generation HTS tapes (BSCCO) consist of multifilamentary composite tapes embedded in a silver matrix. The typical critical current density is approximately 14 kA/cm2. However, the resistance reached by the SFCL when normal state occurs is not high enough to limit the fault current, making necessary long lengths of tapes (~5 km) for limiting purposes. The recently development of coated conductors composites with high resistivity metal substrate have succeeded the BSCCO tapes which are based on YBCO textured film. Upon carrying a critical current density of 13.6 kA/cm2, YBCO tapes are well known for their high n-index value (approximately 30), fast transition response after fault, and high electrical resistance in the normal state. In this work, we will present the electrical and magnetic performance of BSCCO and YBCO tapes (short samples of 0.2 m) using several techniques to characterize the properties of the HTS tapes. It was also performed analysis with DC and AC currents peaks with strength of 3 to 7 times the critical current (I=720 A to 1700 A) lasting 1 to 5 cycles (16 to 80 ms) in order to verify the recovery characteristics in an element with 4 tapes in a parallel connection. And with those characteristics we designed and constructed and measured in AC current a SFCL prototype (Ipeak = 2 kA) consisting in 16 elements to use in the grid (220 V - 60 Hz) under operational conditions.

Limitadores de corrente supercondutores resistivos (LCSR) são dispositivos com características elétricas próximas ao ideal quando ocorre a transição do estado supercondutor para o estado normal, limitando a corrente de falta através da inserção rápida de uma resistência na rede. A viabilidade técnica e econômica destes limitadores aumentou após o desenvolvimento dos supercondutores de alta temperatura crítica HTS. A primeira geração de fitas HTS (BSCCO) consiste em multifilamentos de material supercondutor embutidos em uma matriz de prata. A densidade de corrente crítica típica é de aproximadamente 140 A/mm2. Contudo, a resistência alcançada pelo LCSR quando atinge o estado normal não é suficiente para limitar a corrente de falta, sendo necessários longos comprimentos de fitas (~5 km) para que a corrente seja limitada. O recente desenvolvimento de fitas supercondutoras de YBCO com filmes finos texturizados e com substrato de alta resistividade superou o desempenho das fitas de BSCCO para esta aplicação. Com uma densidade de corrente crítica de 136 A/mm2, as fitas de YBCO são bem conhecidas pelo seu alto valor de índice n (aproximadamente 30), rápida resposta de transição após falta e alta resistência elétrica no estado normal. Neste trabalho foram analisados o comportamento elétrico e magnético das fitas de BSCCO e YBCO (em amostras curtas de 0,2 m) utilizando diferentes técnicas de caracterização das propriedades das fitas HTS. A partir destes resultados, medidas com pulsos de corrente DC e AC com intensidades de 3 a 7 vezes a corrente crítica do sistema (I=720 A a 1700 A) com duração de 1 a 5 ciclos da rede em 60 Hz (16 a 80 ms) foram realizados de forma a obter as características do tempo de recuperação em um elemento contendo 4 fitas em paralelo (0,4 m). Os resultados permitiram o projeto, construção e medidas em corrente AC de um protótipo LCSR (Ipico = 2 kA) contendo 16 elementos sob condições normais de operação da rede (220 V - 60 Hz). / Resistive Superconducting fault current limiter (SFCL) are devices with electrical behavior near the ideal when it changes its state from the superconducting to the normal state, limiting the fault current by the insertion of a fast transition resistance in the grid. The technical and economical feasibility of these limiters arose after the development of the high critical temperature superconductors HTS. First generation HTS tapes (BSCCO) consist of multifilamentary composite tapes embedded in a silver matrix. The typical critical current density is approximately 14 kA/cm2. However, the resistance reached by the SFCL when normal state occurs is not high enough to limit the fault current, making necessary long lengths of tapes (~5 km) for limiting purposes. The recently development of coated conductors composites with high resistivity metal substrate have succeeded the BSCCO tapes which are based on YBCO textured film. Upon carrying a critical current density of 13.6 kA/cm2, YBCO tapes are well known for their high n-index value (approximately 30), fast transition response after fault, and high electrical resistance in the normal state. In this work, we will present the electrical and magnetic performance of BSCCO and YBCO tapes (short samples of 0.2 m) using several techniques to characterize the properties of the HTS tapes. It was also performed analysis with DC and AC currents peaks with strength of 3 to 7 times the critical current (I=720 A to 1700 A) lasting 1 to 5 cycles (16 to 80 ms) in order to verify the recovery characteristics in an element with 4 tapes in a parallel connection. And with those characteristics we designed and constructed and measured in AC current a SFCL prototype (Ipeak = 2 kA) consisting in 16 elements to use in the grid (220 V - 60 Hz) under operational conditions.

[pt] O primeiro material supercondutor de alta temperatura foi descoberto em 1986. Desde então foram sintetizados mais de 150 novos supercondutores (cupratos, bismutatos, boretos e fulerenos) com temperatura crítica superior à temperatura de 23,3 K, a temperatura crítica mais alta entre os materiais supercondutores de baixa temperatura. Muitos destes novos materiais supercondutores têm provocado interesse acadêmico, sendo utilizados, por exemplo, para a compreensão do fenômeno de supercondutividade a alta temperatura. No entanto, há famílias supercondutoras que possuem propriedades atraentes para o desenvolvimento de novas tecnologias voltadas particularmente para sistemas elétricos de potência, medicina e transporte (veículo Maglev). Dois supercondutores da família BSCCO, Bi2Sr2CaCu2O8+x (Bi-2212) e Bi2Sr2Ca2Cu3O10+x (Bi-2223), estão entre os mais pesquisados para aplicação em escala industrial no setor elétrico. Uma projeção do mercado de dispositivos para o setor elétrico, à base de supercondutores de alta temperatura, aponta que este mercado deve movimentar em torno de 47 bilhões de dólares em 2020, tendo como destaques, com quase 90% deste mercado, limitadores de corrente de curtocircuito, transformadores e SMES (Sistema Magnético Supercondutor de Armazenagem de Energia). A presente tese se propôs a contribuir para o desenvolvimento de uma nova tecnologia de produção de limitadores de corrente de curto-circuito (LCC) à base da fase supercondutora Bi-2212. Esta tecnologia baseia-se na produção de formas maciças (blocos) da fase Bi-2212, para a confecção de LCC, através da fusão parcial e solidificação peritéticas desta fase. Este método difere substancialmente do método de fusão completa, usualmente empregado para a obtenção destes blocos. Para o desenvolvimento e o aperfeiçoamento desta nova tecnologia foi necessário estudar a fusão e a solidificação peritéticas da fase Bi- 2212. Com este intuito, para acompanhar esses dois processos foram utilizadas técnicas de observação in situ, assim como análise de amostras temperadas. As propriedades supercondutoras foram estudadas por meio das caracterizações eletromagnéticas. Com base nestes estudos foi desenvolvido um ciclo térmico que proporciona uma densidade de corrente crítica da fase Bi-2212 na forma maciça superior a 1000A/cm2, em corrente direta, a 77K e sem campo magnético externo. Este valor confirma a viabilidade do método para a produção de material para LCC. / [en] High temperature superconductivity was discovered in 1986. Since then more than 150 new superconductors (cuprates, bismuthates, borides and fullerite) with critical temperature higher then 23,3K (the highest critical temperature for low temperature superconductors) have been synthesized. Many of them rise interest from the scientific viewpoint and are suitable for investigations focusing the phenomena of high temperature superconductivity. However, some superconducting families display properties that are attractive for applications in electrical power systems, medicine and transport. Two superconductors from the BSCCO family, Bi2Sr2CaCu2O8+x (Bi-2212) e Bi2Sr2Ca2Cu3O10+x (Bi-2223), are among the most studied for application in electrical power systems at industrial scale. One prognostic for the market of superconducting electrical devices points out that this market will represent more than 47 billion dollars in the year 2020. More than 90% of this market will be dominated by devices such as: fault current limiters (FCL), transformers and superconducting magnetic energy storage systems (SMES). The present thesis aims to contribute for the development of a new technology for production of fault current limiters, based on the Bi-2212 phase, the partial melt method. This method involves peritectic fusion and solidification of the Bi-2212 phase and is substantially different from the complete melt processing usually used for production of Bi- 2212 blocks. The peritectic fusion and solidification of the Bi-2212 phase were investigated by quenching and in situ techniques. Superconducting properties were also studied by electromagnetic measurements. Based on these studies, a thermal cycle was established which results in a critical current density in bulk form, of the Bi-2212 phase, superior to 1000A/cm2, in direct current, at 77K and zero field. This value confirms the potential of the method to produce material for FCL.

Ce mémoire traite de la limitation de courant à partir de supraconducteurs HTc. L'utilisation de la transition naturelle d'un état supraconducteur vers un état dissipatif est envisagée pour limiter les courants de défaut sur les réseaux de distribution électrique. Cette application de la supraconductivité est très prometteuse puisque aucune solution conventionnelle ne réalise cette fonctionnalité pour la haute tension. Le gain réalisé par l'installaton de limiteurs de courant serait une densification des réseaux électriques et une amélioration de la qualité de l'énergie distribuée. Cette étude se scinde en deux points. Le premier concerne l'étude expérimentale du comportement de différents matériaux supraconducteurs HTc pour la limitation de courant. Cette caractérisation a été menée en régime nominal alternatif (mesures des pertes) et en régime de défaut. Dans le cadre de cette étude, le matériau YBCO mono domaine a fait l'objet d'une analyse approfondie à haute température. Un travail de modélisation numérique visant à prédire les conséquences d'une transition inhomogène et à estimer les pertes en régime assigné a également été mené. Afin de valider la faisabilité d'un appareillage haute tension, un démonstrateur 1 kV / 100 A constitué de 43 méandres d'YBCO texturé a été testé à une température de 90,5 K. Cette étude s'est également focalisée sur la dynamique de la transition des matériaux supraconducteurs. Nos expériences semblent montrer que la transition est plus homogène au voisinage de Tc. Cette observation est principalement justifiée par la faible valeur de Jc au voisinage de Tc, par des considérations thermiques (meilleure propagation du front de transition) et magnétiques (ancrage magnétique et mécanisme avalancheux de la transition différents près de Tc). Des résultats expérimentaux mettent également le doigt sur l'importance des échanges thermiques latéraux sur la transition des supraconducteurs. L'analyse menée montre que l'énergie dissipée au sein du matériau étudié semble l'être de façon localisée.

An RF switch in substrate integrated waveguide (SIW) technology for X-band is designed and demonstrated. Design is based on embedding shunt pin diodes of the switch in an evanescent mode waveguide filter. At reverse bias, pin diodes formed a part of filter&#039 / s capacitances. Thus switch also functions as a filter when it is in &ldquo / on&rdquo / state. At forward bias of diodes, capacitances of the filter are short circuited to obtain a good isolation. The same circuit structure is used to design a tunable filter and an RF power limiter which also functions as a filter. Several RF functions usually used in RF frontends (power limiting, filtering, switching) are combined in a single circuit which helps miniaturization of the frontend. The circuit can be produced with standard PCB and chip&amp / wire technology. The circuits developed have comparable performances with microstrip counterparts and they are advantageous to use in microwave systems using SIW as the basic transmission medium and need filtering functionality.