The diploma thesis is focused on the innovation of partially user-unsuitable software which is used in the CVVOZE short-circuit laboratory for the evaluation of testing of switching and protection devices. The introductory part of the work presents a technical laboratory, which is used for research and development in the field of electrical devices with possibility of testing of short circuits and over-currents. At the first part of thesis, there is made a description of the technical laboratory. The following past is a chapter with basic introduction of tested devices and standard testing conditions of electrical devices in the laboratory. Then following a description of the original evaluation software is made and its shortcomings are pointed out. The practical part is devoted to the creating in LabVIEW, implementation and verification of the functionality of the new evaluation software.

This work deals with ecological design and appraisal of quality of the electronic devices throughout their life cycle. This area known worldwide as Eco-Design, becomes an integral part of all electro technical productions. This work brings out not only conception of the Eco-Design, but also next related areas with the aim to decrease limitation of negative impact on environment. At the end of the work is compared and summarized the ecological evaluation of the concrete product types.

The thesis deals with the design of a transformer station for the outgoing power of cogeneration unit with an electric capacity of up to 1 MW. The thesis describes the design procedure of individual devices such as a transformer with a nominal ratio 22/0,4 kV, high voltage switchgears and low voltage switchgears. With the proper selection of the transformer, along with the technical parameters, the economic benefits that come from its purchasing and operating costs with the transformer operation are also considered. Based on this, the economic comparison of selected types of oil transformers during 20 years is also developed. Another part of the thesis deals with HV and LV switchgears, which are dimensioned according to shortcircuit conditions in the transformer station. In conclusion this work deals with the grounding of a transformer station and design protection in accordance PPDS.

This paper deals with mechanical switch in circuit breaker designed for low voltage. The goal of this thesis was to analyze switching mechanism both theoretically and practically. Theoretical analysis consist of study different types of switching mechanism and analytical calculations of acceleration speed and trajectory. Practical analysis has been made taking a video with high speed camera of real switching mechanism of a circuit breaker and software analysis of the data. The next part of a thesis is about 3D modeling, animating and simulating of a switchgear switching mechanism.

This master thesis deals with determination of temperature field in a real circuit breaker. This issue is solved by analysis of measured emission spectra at selected points of the circuit breaker. Spectral line ratios and Boltzmann plot are used for calculation of temperature. These methods are based on elemental analysis of plasma. The main result is finding significant changing of chemical composition of plasma beyond determination of temperature field.

Vattenfall Eldistribution AB är en av Sveriges största nätägare och har som mål att få Sverige fossilfritt inom en generation. För att täcka Sveriges elenergibehov på ett fossilfritt sätt krävs det fler förnybara produktionsanläggningar. En av de produktionsanläggningarna som växer mest just nu är solcellsanläggningar. Svenska standarder har regler för hur produktionsanläggningar ska utformas. Det ställs bland annat krav på hur den manuella frånkopplingen ska fungera och att det måste finnas en brytare som kan frånskilja hela produktionsanläggningen, även kallad produktionsbrytare. På grund av olika tolkningar har denna brytare kunnat placeras på olika sätt, men nu vill Vattenfall Eldistribution AB med hjälp av detta arbete ta fram ett standardiserat sätt att placera produktionsbrytaren på. Därför var huvudmålet med arbetet att ta fram riktlinjer för hur kunder till Vattenfall Eldistribution AB ska placera produktionsbrytaren i anläggningen. Arbetet presenterar en övergriplig beskrivning över hur en solcellsanläggning kan se ut samt hur mängden av dessa anläggningar i Sverige har förändrats. Då statistiken visat att antalet produktionsanläggningar ökat varje år blir det allt viktigare att det finns tydligare riktlinjer från nätägare. Dessutom undersöks hur Vattenfall Eldistribution AB behandlar en förfrågan att installera solceller. Genom beräkningar av elnätet avgörs hur anslutningen av produktionsanläggningen kommer att gå till. För att uppnå ett resultat krävdes det att ta in information från flera källor. Vattenfall Eldistribution AB delade med sig av vad som var viktigt för dem och hur de önskar att installationerna är utformade. Som komplement till Vattenfall Eldistribution AB:s yttrande granskades relevanta standarder och föreskrifter. För att ytterligare motivera placeringen till kunder har hänsyn tagits till brandkårens önskemål om solcellsanläggningar. Baserat på informationen från samtliga källor togs riktlinjer fram. Dessa riktlinjer presenterar olika placeringar av produktionsbrytaren. För varje placering beskrivs fördelar och nackdelar. Slutsatserna av arbetet är att produktionsbrytaren behöver placeras utomhus, antingen på byggnadens fasad alternativt i mätarskåpet om det befinner sig utomhus. Utöver placeringen av produktionsbrytaren behöver även växelriktaren till anläggningen uppfylla de krav som ställs av förordningar vilket lättast görs genom att välja en växelriktare som är med i listan ”Rikta Rätt” från Energiföretagen. / Vattenfall Eldistribution AB is one of Sweden's largest grid owners and aims to make Sweden fossil-free within one generation. In order to cover Sweden's electrical energy needs in a fossil-free way, more renewable production plants are required. One of the production plants that is growing the most right now is solar cell plants. Swedish standards have rules for how production plants must be designed. Among other things, there are requirements on how the manual disconnection of the solar cells should work and that there must be a circuit breaker that can disconnect the entire production plant, also called a production circuit breaker. Due to different interpretations, this circuit breaker has been allowed to be placed in different ways, but now Vattenfall Eldistribution AB wants to use this work to develop a standardized way to install the production circuit breaker. Therefore, the main goal of the work has been to produce guidelines for how customers of Vattenfall Eldistribution AB should place the production circuit breaker in the plant. The work presents a comprehensive description of what a solar cell installation might look like and how the amount of these facilities have changed in Sweden. As the statistics show that the number of production facilities increases every year, it is important that there are clearer guidelines from grid owners. In addition, how Vattenfall Eldistribution AB handles a request to install solar panels has been investigated. Through calculations of the electricity network, it is determined how the connection of the production plant will be carried out. In order to achieve a result, it was necessary to gather information from several sources. Vattenfall Eldistribution AB shared what was important to them and how they would like the installations to be designed. As a supplement to Vattenfall Eldistribution AB's opinion, relevant standards and regulations were examined. In order to further justify the placement to customers, consideration was also given to the fire department's requests for solar cell installations. Based on the information from all sources, guidelines were created. These guidelines present different locations of the production circuit breaker. For each location the advantages and disadvantages are described. The conclusions of the work are that the production circuit breaker needs to be placed outdoors, either on the facade of the building or alternatively in the meter cabinet if it is outdoors. In addition to the location of the production circuit breaker, the inverter for the plant also needs to meet the requirements set by regulations, which is done by choosing an inverter that is on the list of "Rikta Rätt" from Swedenergy.

The interest of using direct current in networks for both transmission and distribution of power is increasing due to the higher efficiency compared to the alternating current used today. As no natural zero crossings exist in direct current, the interruption of fault currents becomes a challenge. Several circuit breaker topologies have been proposed to fulfill the requirements for DC grids. One such topology is the hybrid DC-breaker consisting of three parallel branches: a mechanical switch, a semiconductor branch, and a metal oxide varistor. The current interruption in the hybrid DC-breaker is made in three steps. A mechanical switch carries the nominal current with low losses during normal operation. When the breaker is tripped to interrupt the current, the mechanical switch is opened and commutates the current into the semiconductor branch. This branch will then conduct the current as the mechanical switch regains its voltage withstand. The semiconductors turn off and force the current into the varistor branch where the magnetic energy is absorbed and the current is forced to zero. This thesis is based on simulations and experiments to obtain design rules for such a DC-breaker. It has been shown that several aspects needs to be considered. Simulations are performed with several different models to obtain the requirements of each of the components in the DC-breaker. First of all, the choice of the semiconductor is important. There are a number of components available in the market, but typically they are optimized for fast switching applications like inverters rather than circuit breaker applications that only requires one single switching. Due to the high current and voltage ratings and the easy control, the IGBT seems to be the best choice among the commercially available components. Simulations on the mechanical switch show that there is an optimal combination of opening time and arc voltage of the to obtain a successful commutation into the semiconductor branch. The actuator is a key component since a relatively low increase in performance of the actuator drive circuit, significantly decreases the requirement of the other components in the DC-breaker. A significant part of the work has been put on the voltage transient during the turn-off of the semiconductor. As the current is forced into the varistor branch, the stray inductance in that loop will result in an over-voltage due to the high current derivative. A new type of snubber has been investigated using another varistor mounted close to the semiconductor. It has been shown that the function of the varistor snubber can be divided into two regions depending on the ratio between the snubber and the main varistor. If the ratio is high enough, the energy absorbed in the snubber varistor is only a few percent of the total energy. / Intresset för att använda likström i både transmission och distribution av elkraft har ökat tack vare en högre verkningsgrad och lägre förluster. En begränsande faktor för utbyggnad av likströmsnät är utvecklingen av brytare för likström. Svårigheten att bryta en likström jämfört med växelström är att det saknas en naturlig nollgenomgång där strömmen kan brytas. För att tvinga fram en nollgenomgång kan man använda en hybrid brytare som består av tre parallella grenar: en mekanisk switch, en gren med krafthalvledarkomponenter och en gren med en varistor. Hybridbrytaren bryter en ström i tre steg. I normalfallet leder den mekaniska kontakten strömmen för att hålla nere de elektriska förlusterna. När strömmen ska brytas öppnas den mekaniska kontakten och strömmen kommuteras över till krafthalvledargrenen. När krafthalvledaren stängs av, trycks strömmen över till den tredje grenen där varistorn begränsar spänningen över brytaren och absorberar den magnetiska energi som finns lagrad i nätet. Strömmen avtar och när systemet är avmagnetiserat når strömmen noll. Denna avhandling sammanfattar ett arbete att med hjälp av simuleringar och experiment få fram designparametrar för en sådan brytare. Flera simuleringsmodeller har av använts för att få fram designkriterier för de olika komponenterna i hybridbrytaren. Ett första steg är att välja krafthalvledarkomponent. Dessa komponenter är främst utvecklade för omvandling mellan lik- och växelström där de slås av och på i korta intervall. En brytartillämpning skiljer sig markant från detta eftersom strömmen bara behöver brytas enstaka gånger vilket ändrar kraven på komponenten. Enkelheten i att kontrollera komponenten tillsammans med dess höga ström- och spänningstålighet gör IGBTn till det bästa valet bland de kommersiellt tillgängliga komponenterna. Simuleringar visar att en optimal design av den mekaniska switchen är en kombination av snabbhet och ljusbågsspänning. En nyckelkomponent är den snabba aktuatorn som driver switchen. En relativt liten förbättring av drivkretsen kan leda till minskade krav och därmed kostnader på övriga komponenter i brytaren. En stor del av arbetet har lagts på att studera den transienta överspänningen då krafthalvledarkomponenten bryter strömmen. Den höga strömderivatan medför att även små ströinduktanser leder till relativt stora överspänningar som riskerar att skada brytaren. En ny typ av snubberkrets, bestående av en mindre varistor som monteras nära krafthalvledaren, har föreslagits. På detta sätt separeras överspänningsskyddet från absorptionen av den magnetiska energin. Experiment och simuleringar visar att om spänningsförhållandet mellan de två varistorerna är tillräckligt stort absorberas endast ett par procent av energin i snubbern. / <p>QC 20150420</p>

High Voltage Direct Current (HVDC) is a rapidly growing form of power transmission that offers advantages with respect to conventional AC networks. One of the key elements that will allow the generalization of the HVDC grids is the Circuit Breaker (CB), which has to interrupt high DC currents in extremely short times. The use of a Thomson coil (TC) to generate high driving forces is being considered as a suitable working principle for the mechanical actuator inside the CB. This thesis presents the design of a concept of a mechanical actuator based on the Thomson coil for SCiBreak AB, a company whose final objective is to create a complete ultra-fast circuit breaker for HVDC lines. The design phase had to face challenges with the high forces required to open a gap between electrical contacts in just a few milliseconds. A detail design for the different components of the actuator was performed and analytical and CAD models of the system were generated. This thesis also included the construction and testing of a prototype at the company’s premises. The final output was the analysis and discussion of the experimental results of the prototype, as well as suggestions for the future development of the mechanical actuator. / Högspänd likström (HVDC, från engelskans High Voltage Direct Current) är en snabbt växande form av kraftöverföring som har många fördelar jämfört med konventionella växelströmsnätverk. Ett av huvudelementen i nätet är strömbrytaren (CB, från engelskans Circuit Breaker), vilken möjliggör avbrott i de höga likströmmarna på extremt korta tider. Användandet av en Thomson-spole (TC, från engelskans Thomson Coil) för att generera höga drivkrafter anses vara en lämplig arbetsprincip för manöverdonet inuti CB. I detta projekt konstruerades ett koncept av ett mekaniskt manöverdon baserat på Thomson-spolen för SCiBreak AB, ett företag vars slutliga mål är att skapa en komplett ultrasnabb strömbrytare för HVDC-linjer. Designfasen mötte utmaningar med de höga krafter som krävs för att öppna ett gap mellan elektriska kontakter på bara några millisekunder. En detaljdesign för de olika komponenterna i manöverdonet utfördes och analytiska och CAD-modeller av systemet genererades. Projektet omfattade också tillverkning och provning av en prototyp i företagets lokaler. Slutprodukten var en analys och en diskussion av prototypens experimentella resultat samt förslag till framtida utveckling av det mekaniska manöverdonet.

Cette thèse traite de la commande hiérarchique de réseaux à courant continu multi-terminaux à haute tension (MT-HVDC) intégrant des sources d'énergie renouvelables à grande échelle. Le schéma de contrôle proposé est composé de quatre ‘couches’ : le contrôle local où se trouvent les convertisseurs de puissance, avec une échelle de temps de l’ordre de la milliseconde ; le contrôle primaire qui est décentralisé et appliqué à plusieurs terminaux avec une échelle du temps de l’ordre de la seconde ; un niveau de commande où la communication est prise en compte et où l’approche de Modèle du Commande Prédictive (MPC) assure la planification de la tension et de la puissance à leur état d'équilibre, pour l'ensemble du système; enfin, le contrôleur de niveau supérieur, qui est principalement basé sur les techniques d'optimisation, où les aspects économiques sont pris en compte (il s’agit du réglage dit tertiaire).Au niveau des convertisseurs, un accent particulier est mis sur les convertisseurs bidirectionnels DC/DC. Dans cette thèse, trois topologies différentes sont étudiées en profondeur: deux phases Dual Active Bridge (DAB), trois phases DAB, et l’utilisation de la technologie Modular Multilevel converter (MMC) comme convertisseur DC/DC. Pour chaque topologie, une commande non-linéaire spécifique est discutée. D’autre part une nouvelle fonction pour le convertisseur DC/DC est étudiée. Il s’agit de son utilisation comme disjoncteur à courant continu (DC-CB). En ce qui concerne le contrôle primaire, qui permet de maintenir le niveau de tension continue dans le réseau, nous avons étudié trois philosophies de contrôle: celle de maître/esclave, celui du contrôle « voltage margin control » et celle de la commande du statisme (droop control). Enfin, nous avons choisi d'utiliser le droop control, entre autres, parce que la communication entre les nœuds n’est pas nécessaire. Concernant la commande secondaire, son principal objectif est de planifier le transfert de puissance entre les nœuds du réseau, qui fournissent la tension et la puissance de référence aux contrôleurs locaux et primaires, même lorsque des perturbations apparaissent. Dans cette partie, nous avons proposé une nouvelle approche pour résoudre les problèmes de flux de puissance (équations non-linéaires) basée sur le théorème du point fixe de l’application contractive. Ceci permet d'utiliser plus d'un slack bus, contrairement à l’approche classique basée sur la méthode de Newton-Raphson. Par ailleurs, le réglage secondaire joue un rôle très important dans les applications pratiques, en particulier lorsque les sources d'énergie renouvelables (variables dans le temps). Dans de tels cas, il est intéressant de considérer des dispositifs de stockage afin d'améliorer la stabilité de tout le système. Il est également possible d'envisager différents types de prévisions (météo, charge, ..) basées sur la gestion des réserves de stockage. Toutes ces caractéristiques ont suggéré l'utilisation d'une approche MPC. Dans ce contexte, plusieurs critères d'optimisation ont été considérés, en particulier la minimisation des pertes de transmission ou des congestions dans le réseau.La tâche principale de réglage tertiaire est de d'atteindre l'optimisation économique de l'ensemble du réseau. Dans cette thèse, nous avons pu maximiser le profit économique du système en agissant sur le marché réel, et en optimisant l'utilisation des périphériques de stockage. Dans le but de mettre en œuvre la philosophie de contrôle hiérarchique présentée dans cette thèse, nous avons construit un banc d'essai expérimental. Cette plate-forme dispose de quatre terminaux reliés entre eux par l'intermédiaire d'un réseau à courant continu, et connectés au réseau principal de courant alternatif. Ce réseau DC peut fonctionner à un maximum de 400 V, et avec une courant maximal de 15 A. / This thesis focuses on the hierarchical control for a multi-terminal high voltage direct current (MT-HVDC) grid suitable for the integration of large scale renewable energy sources. The proposed control scheme is composed of 4 layers, from the low local control at the power converters in the time scale of units of ms; through distributed droop control (primary control) applied in several terminals in the scale of unit of seconds; and then to communication based Model Predictive Control (MPC) that assures the load flow and the steady state voltage/power plan for the whole system, manage large scale storage and include weather forecast (secondary control); finally reaching the higher level controller that is mostly based on optimization techniques, where economic aspects are considered in the same time as longer timespan weather forecast (tertiary control).Concerning the converters' level, special emphasis is placed on DC/DC bidirectional converters. In this thesis, three different topologies are studied in depth: two phases dual active bridge (DAB), the three phases DAB, and the use of the Modular Multilevel Converter (MMC) technology as DC/DC converter. For each topology a specific non-linear control is presented and discussed. In addition, the DC/DC converter can provide other important services as its use as a direct current circuit breaker (DC-CB). Several operation strategies are studied for these topologies used as DC-CB.With respect to primary control, which is the responsible to maintain the DC voltage control of the grid, we have studied several control philosophies: master/slave, voltage margin control and droop control. Finally we have chosen to use droop control, among other reasons, because the communication between nodes is not required. Relative to the secondary control, its main goal is to schedule power transfer between the network nodes providing voltage and power references to local and primary controllers, providing steady state response to disturbances and managing power reserves. In this part we have proposed a new approach to solve the power flow problem (non-linear equations) based on the contraction mapping theorem, which gives the possibility to use more than one bus for the power balance (slack bus) instead of the classic approach based on the Newton-Raphson method. Secondary control plays a very important role in practical applications, in particular when including time varying power sources, as renewable ones. In such cases, it is interesting to consider storage devices in order to improve the stability and the efficiency of the whole system. Due to the sample time of secondary control is on the order of minutes, it is also possible to consider different kinds of forecast (weather, load,..) and to achieve additional control objectives, based on managing storage reserves. All these characteristics encourage the use of a model predictive control (MPC) approach to design this task. In this context, several possibilities of optimization objective were considered, like to minimize transmission losses or to avoid power network congestions.The main task of tertiary control is to manage the load flow of the whole HVDC grid in order to achieve economical optimization. This control level provides power references to the secondary controller. In this thesis we were able to maximize the economic profit of the system by acting on the spot market, and by optimizing the use of storage devices. In this level it is again used the MPC approach.With the aim of implementing the hierarchical control philosophy explained in this thesis, we have built an experimental test bench. This platform has 4 terminals interconnected via a DC grid, and connected to the main AC grid through VSC power converters. This DC grid can work at a maximum of 400 V, and with a maximum allowed current of 15 A.

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-17T13:51:49Z No. of bitstreams: 1 HENRIQUE NUNES DE SANTANA – DISSERTAÇÃO (PPGEE) 2017.pdf: 2930914 bytes, checksum: a4c0e297d62f2854c085762512fb6f16 (MD5) / Made available in DSpace on 2018-04-17T13:51:49Z (GMT). No. of bitstreams: 1 HENRIQUE NUNES DE SANTANA – DISSERTAÇÃO (PPGEE) 2017.pdf: 2930914 bytes, checksum: a4c0e297d62f2854c085762512fb6f16 (MD5) Previous issue date: 2017-08-18 / Capes / Neste trabalho, é avaliada aplicabilidade de sensores de acoplamento capacitivo na detecção dos sinais emitidos por arcos elétricos em contatos de disjuntores. Adicionalmente, é investigada a possibilidade de correlacionar estes sinais com nível de degradação dos contatos de arco. A aplicabilidade dos sensores é avaliada por meio da comparação dos sinais detectados pelos mesmos, com os sinais detectados por uma antena direcional em banda larga, tanto no domínio do tempo quanto no domínio da frequência. Para a análise da correlação entre o nível de degradação dos contatos de arco e os sinais detectados, atributos de estatística descritiva da duração e da energia dos sinais foram avaliados. A análise dos resultados evidenciou que os sensores de acoplamento capacitivo são capazes de detectar os sinais emitidos pelos arcos elétricos. Também foi evidenciado que a sensibilidade de detecção dos sensores depende da posição na qual foram instalados ao longo do polo analisado. No caso dos disjuntores utilizados neste trabalho, a melhor posição para a instalação dos sensores foi a posição mais próxima do terminal inferior do polo. A flexibilidade e o valor da constante dielétrica devem ser avaliados no momento da escolha do material empregado na confecção dos sensores, uma vez que sensores pouco flexíveis podem sofrer danos ao serem instalados no polo do disjuntor e, constantes dielétricas elevadas podem prejudicar os ganhos dos respectivos sensores. A correlação entre os sinais dos arcos elétricos detectados pelos sensores e o nível de degradação dos contatos de arco é possível, quando os atributos estatísticos da média, desvio padrão, curtose e mediana obtidos da energia dos referidos sinais são avaliados. / In this work, is evaluated the applicability of capacitive coupling sensors in the detection of signals emitted by electric arcs in circuit breaker contacts. In addition, the possibility of correlating these signals with the arcing contacts degradation level is investigated. The sensors applicability is investigated by comparing the signals detected by them with the signals detected by a broadband directional antenna in both time and frequency domain. For the analysis of the correlation between the arcing contacts degradation level and the detected signals, descriptive statistical attributes of the duration and energy of the signals were evaluated. The analysis of the results showed that the capacitive coupling sensors are able to detect the signals emitted by the electric arcs. It was also evidenced that the sensor detection sensitivity depends on the position in which they are installed along the analyzed pole. In the case of the circuit breakers used in this work, the best position for the installation of the sensors was the one closest to the lower terminal of the pole. The flexibility and value of the dielectric constant must be evaluated when choosing the material used in the construction of the sensors, since weak sensors can be damaged when installed at the pole of the circuit breaker, and high dielectric constants can affect the gains of the respective sensors. The correlation between the electric arcs signals detected by the sensors and the arcing contacts degradation level is possible, when the statistical attributes of the mean, standard deviation, kurtosis and median obtained from the energy of these signals are evaluated.