abstract: Transmission line capacity is an obstacle for the utilities because there is a load increment annually, and new power plants are being connected, which requires an update. Energy router (ER) is a device that provides an additional degree of freedom to the utilities by controlling the reactive power. The ER reactive power injection is demonstrated by changing the line's reactance value to increase its capacity and give the utility a deferral time for the project upgrade date. Changing the reactance manually and attaching Smart Wire's device to the branches have effectively solved the overload in three locations of a local utility in Arizona (LUA) system. Furthermore, electric vehicle charging stations (EVCSs) have been increasing to meet EV needs, which calls for an optimal planning model to maximize the profits. The model must consider both the transportation and power systems to avoid damages and costly operation. Instead of coupling the transportation and power systems, EVCS records have been analyzed to fill the gap of EV demand. For example, by accessing charging station records, the moment knowledge of EV demand, especially in the lower order, can be found. Theoretically, the obtained low-order moment knowledge of EV demand is equivalent to a second-order cone constraint, which is proved. Based on such characteristics, a chance-constrained (CC) stochastic integer program for the planning problem is formulated. For planning EV charging stations with ER, this method develops a simple ER model to investigate the interaction between the mobile placement of power flow controller and the daily pattern of EV power demand. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2020

La croissance des unités de distribution des ressources énergétiques ainsi que l'intégration des nouvelles technologies dans la production et le stockage d'énergie, ont imposé un contrôle nouveau et de nouvelles stratégies opérationnelles. Grâce à sa capacité de stockage et étant considérée comme une énergie propre; la pile à combustible (Pac) est l'une des technologies les plus prometteuse en tant que source d'énergie stationnaire dans les réseaux micro et aussi dans les applications de transport. Par conséquent, deux sujets principaux sont abordés dans cet ouvrage, la conception et l'installation d'un banc d'essai complet instrumenté a membrane échangeuse de polymère (PEM) Pac et de conception et l'essai expérimental d'une nouvelle stratégie de contrôle dynamique d'échange de l'énergie pour les systèmes multi - source et multi - charge. Pour définir le test instruments banc exigences, un examen complet de modèle dynamique est donné dans la première partie. Dans la prochaine section seront inclues, les renseignements concernant la configuration de la conception et la mise en œuvre de banc d'essai de Pac, i.e., critères de spécification des instruments, acquisition, et affichage des données du système. Des résultats expérimentaux sont réalisés afin de démontrer les potentialités de l'installation. Dans le chapitre suivant, une nouvelle stratégie de contrôle dynamique de l'énergie d'échange (DSER) sera introduite et testée par simulation et expérimentalement dans un système à deux ports. Afin d'établir une comparaison et d'intégrer la DSER dans une application Pac, un système à trois ports - y compris un modèle statique de Pac - et deux différentes approches de contrôle, seront testés par simulation dans le cinquième chapitre. La thèse s’achèvera par quelques conclusions et quelques thèmes de recherche potentiels générés à partir de ce travail. / The growth of distributed energy resources together with the incorporation of new technologies in the generation and storage of energy are imposing new control and operational strategies. Due to its storage capability and that it is considered to be clean energy; fuel cell (FC) is one of the most promissory technologies as a stationary energy source in micro grids and also in transportation applications. Therefore, two main issues are addressed in this work; the conception, design, and setup of a fully instrumented test bench for proton exchange membrane (PEM) FC stacks and the design and experimental test of a new dynamic energy-exchange control strategy for multi source and multi load systems. To define the test bench instrument requirements, in the first part a complete dynamic model review is given. In the next section, relevant information regarding the setup of the FC test bench design and implementation is included, i.e., specification criteria of the instruments and acquisition and data display system. Some experimental results are performed in order to demonstrate the potentialities of the setup. In the following chapter, a new dynamic energy exchange control strategy (DSER) is introduced and tested in a two port system via simulation and experimentation. In order to establish a comparison and integrate the DSER in a FC application, in the fifth chapter a three port system – including a static model of FC – and two different control approaches, are tested via simulation. The thesis is closed with some concluding remarks and some potential research topics generated from this work.

The growth of distributed energy resources together with the incorporation of new technologies in the generation and storage of energy are imposing new control and operational strategies. Due to its storage capability and that it is considered to be clean energy; fuel cell (FC) is one of the most promissory technologies as a stationary energy source in micro grids and also in transportation applications. Therefore, two main issues are addressed in this work; the conception, design, and setup of a fully instrumented test bench for proton exchange membrane (PEM) FC stacks and the design and experimental test of a new dynamic energy-exchange control strategy for multi source and multi load systems. To define the test bench instrument requirements, in the first part a complete dynamic model review is given. In the next section, relevant information regarding the setup of the FC test bench design and implementation is included, i.e., specification criteria of the instruments and acquisition and data display system. Some experimental results are performed in order to demonstrate the potentialities of the setup. In the following chapter, a new dynamic energy exchange control strategy (DSER) is introduced and tested in a two port system via simulation and experimentation. In order to establish a comparison and integrate the DSER in a FC application, in the fifth chapter a three port system - including a static model of FC - and two different control approaches, are tested via simulation. The thesis is closed with some concluding remarks and some potential research topics generated from this work.

In the era of ever-increasing electrification, power-electronic converters play the crucial role of transforming electrical energy from one form to another. However, converters today face multiple challenges in meeting ever-growing demands for higher power density, broader operation ranges, and lower costs. The cost-benefits of economies of scale further emphasize the need for modular and scalable converters. While no single converter for high-power applications satisfies all criteria, the modular multilevel converter (MMC) emerges as the clear frontrunner. MMC is extremely modular, being developed using multiple smaller units or building blocks called power electronic building blocks (PEBBs) or submodules (SMs). The SMs are themselves developed using fast-switching low-voltage (LV) semiconductors meaningfully combined with energy storage components like capacitors or batteries. MMCs are highly modular and scalable and have a very broad operation range, making them a key solution already used today for a wide range of high-voltage applications like high-voltage direct-current (HVDC) transmission. However, the use of voluminous and heavy capacitors in SMs also makes MMCs much lower in power density compared to other similar voltage source converters (VSCs). Employing at least twice the number of devices compared to a conventional two-level VSC for the same ratings also increases the converter costs. These challenges have hindered MMC applications in medium-voltage (MV) and more power-dense HVDC systems. This research aims to overcome these limitations by enhancing MMCs in terms of power density, efficiency, and cost-effectiveness. These modifications would expand MMC's applications to much broader HV and MV markets. Three fundamental aspects are targeted to achieve such improvements: Topology, Components, and Controls. The first modification focuses on changing the topology by replacing some fast-switching LV-switch-based SMs with fewer low-frequency HV/MV switches. This greatly reduces the total number of components and, when combined with intelligent control, decreases costs and losses. The second modification focuses on components, proposing the replacement of fully controlled MV switches with more efficient and cost-effective but partially controlled ones like thyristors. Despite thyristors' historical controllability challenges, incorporating SMs can help resolve control challenges, creating a modular, scalable converter with a wide operation range, high power density, and lower costs. The third avenue explores advanced control strategies while maintaining the traditional MMC topology. By accelerating and precisely controlling the capacitor current, the SM capacitor energy, SM capacitor size can be significantly reduced. Although these control methods are complex, they offer potential improvements across all five criteria: modularity, scalability, power density, cost, and operational range. These innovations extend MMCs' applicability to emerging fields such as energy storage systems, electric vehicle charging stations, motor drives, and data centers. Moreover, these modifications enhance MMCs for traditional high-voltage direct-current transmission applications. The research emphasizes the advantages and addresses each modification's limitations, paving the way for a more efficient and versatile power electronics technology. / Doctor of Philosophy / In our electrically powered world, the unsung workhorse is the power(-electronic) converter. Power converters play the crucial role of transforming electrical energy from one form to another using switches that can turn on and off to accurately control the flow of electrical energy. Power converters are critical to integrating systems at different voltage, current, and power ratings. For instance, power converters enable low-power systems like cellphone chargers and high-power industrial drives to be integrated into the same interconnected power grid. However, these converters face challenges in adapting to the evolving demands of our modern world. The expectations from power converters are high – they need to be affordable, lightweight, and capable of processing large amounts of power in a compact size. Additionally, modularity and scalability are desired qualities to enable economies of scale and bring the total cost down. Yet, finding a converter that fulfills all these criteria remains a challenge. The modular multilevel converter (MMC) is a promising power converter developed to address most of these considerations. Currently employed in high-power, high-voltage applications such as transmitting energy over vast distances or linking power grids between countries, the MMC is constructed using smaller power units or building blocks called power electronic building blocks (PEBBs) or submodules (SMs). These SMs utilize fast-switching low-voltage switches along with energy storage components like capacitors or batteries. Despite its versatility, the MMC faces many limitations. The main challenge for MMCs is the inability to process more power in lower volume, commonly referred to as power density. The MMC power density is low due to the use of large capacitors or batteries. Additionally, it utilizes twice the number of switches compared to traditional non-modular power converters for the same rating, leading to higher costs. These challenges restrict its application in medium-voltage and power-dense high-voltage high-power systems. This research aims to address these challenges, focusing on enhancing the power density and cost-effectiveness of MMCs. Three key areas of MMC are targeted for improvement: topology, components, and controls. Firstly, MMC's structure is reimagined, replacing many low-voltage switches with fewer medium- or high-voltage, fully-controlled switches. Such a system is referred to as a hybrid MMC, and this reduces the converter volume and costs. This adjustment has the added benefit of making the converter more efficient. Secondly, the focus is also on the components used to develop hybrid MMCs. Instead of fully controlled medium- or high-voltage switches, partially controlled switches like thyristors provide advantages like lower losses and higher power ratings. However, these partially controlled switches have traditionally been very difficult to control. Despite historical controllability challenges, incorporating these partially controlled switches in conjunction with smart control of SMs addresses control issues, creating a modular, scalable converter with high power density and lower costs. The third enhancement involves fundamental improvements to MMC controls. By managing the energy flow to the capacitor at a much faster rate and precision than conventional methods, the size of a critical component can be significantly reduced, opening avenues for overall improvements. Furthermore, such fast control introduces additional challenges like active control in the face of non-idealities and higher losses. This dissertation further meaningfully addresses these challenges to develop a much more power-dense MMC. These improvements transform the MMC and its variants into a versatile power converter family that can extend much beyond traditional MMC applications of high-voltage transmission applications. With these modifications, the MMC can be further positioned as an excellent candidate to contribute towards energy storage systems, electric vehicle charging stations, industrial-level motor drives, dc microgrids, and data centers, meeting the diverse needs of our equally diverse and ever-more electrified world.