Thesis Supervisor: Cristina González Morán.
Erasmus Mundus Master Course in Sustainable Transportation and Electrical Power Systems at the University of Oviedo.

Electrical energy situation analysis oriented to massive distributed generation penetration in Asturias by Jorge Palacio Sánchez.
Thesis Supervisor: Cristina González Morán.
M.S. Industrial Engineering (electrical specialized). University of Oviedo.

Design and construction of an isolated DC to DC switching converter for integration of energy storage systems in power electronic applications  by Sarah Saeed Hazkial Gerges.

Abstract: With the current trend towards greener energy sources, the integration of Energy Storage Systems (ESS) is the key to sustain the grid against fluctuations of energy generation. This raises a major concern for the inclusion of an efficient, fully controllable power conversion stage to allow an intermediate processing of energy flow. The Dual-Active-Bridge (DAB) converter provides full controllability as well as galvanic isolation. DC-DC Isolated conversion is a critical process in some applications such as Electric (EV) and Hybrid Electric Vehicles (HEV). Also linking ports up in a Multi-port DAB converter via multiport transformer allows for the integration of additional energy sources to the system. This converter can thus be employed in applications ranging from a front-end converter in points of common coupling at facilities, to a high power modular structure used on distribution system levels. The motivation behind the thesis is to study the Dual-Active-Bridge bidirectional dc-dc converter topology, and validate its operation for a 2kW rated power setup. A starting approach for the design procedure, covered in this work, is to employ the converter as a unidirectional power flow converter, supplying a load that resembles the behavior of a typical micro-grid, such as a resistance in parallel with a DC link. Thus, the operation of the converter at rated power can be analyzed, studied and optimized.

Design of a Three-port Solid State Transformer for High Power applications by Guirguis Zaki Guirguis Abdelmessih.

Abstract: In this thesis, a Three-Port Active Bridge converter for high power high voltage application is designed. The design includes the Solid state high frequency transformer, and the required reactive elements the series inductors, and the DC-link capacitors. Also the choice of the switches, and the heat sink is defended, and a design of a stack for them is made, this stack will include also the driver boards of the switches and the capacitors with the bus-bars for the DC-link. The thesis also presents a simulation for each part, and a final simulation for the real model containing almost all the losses and parasitics elements. Using simulation based tools, the design for each of the parts and the full converter assembly is achieved. The simulation includes losses calculation and considers the effects of parasitic elements. The selected design is compared versus a Half-Bridge Triple Active Port topology, in order to analyze the differences in terms of efficiency, performance and reliability. Finally a simulation is presented to illustrated the behavior of the full model under the closed loop condition.

Fault Detection in the DC Bus System of a Vehicle by Octavian Rotariu.

Abstract: In this thesis, the topic of fault detection in the DC and communication buses of avehicle was addressed. Typical fault detection methods were examined and the most appropriate one for the automotive DC bus was further investigated. More techniques commonly used in aviation are investigated and compared. A Matlab Simulink simulation model for reflectometry techniques (Time Domain, Sequence Time Domain, Spread Spectrum-Time Domain and a new Spread Spectrum Frequency Shift Time Domain Technique) was developed and verified experimentally for Time  Domain Reflectometry in coaxial cables and CAN twisted pair wires. Since in a fault condition an impedance variation occurs which causes different reflections of the voltage wave, it is possible to determine the fault condition and its spatial location in a cable. Different cross-correlation and wavelet analysis digital signal processing techniques were tried out.

Investigations on Reactive Power Compensation for a Double Active Bridge with a Planar Transformer by Javier Gómez-Aleixandre Tiemblo.
Abstract: In the future, the power system will be a set of intelligent grids (smart grids) with the generation close to the demand (micro grids). The ultimate goal will be to accomplish most of the energy demand with clean and renewable sources. The problem of this energy sources is that they are volatile, and thus the generation may not match with the demand in some instants. In order to solve this, energy storage systems are required to absorb the extra power when there is more generation than demand, and releasing it in the other case. The objective of this thesis is to study the interconnection between these grids and the energy storage with an isolated power converter. A first overview around the different possible converters is covered in order to justify the selection: a dual active bridge (DAB). The behaviour of the DAB was then explained under different situations. Especial interest is paid in the effect of the dead time in the behaviour of the converter and the excessive reactive power. Finally, a control of the power flow in this converter is tested with a variable load. It is also tested an algorithm to compensate the effect of the dead time.
Thesis Supervisor: Pablo García.
Master Course in Electrical Energy Conversion and Power Systems at the University of Oviedo.

A Detailed Study of Power Flow Solution Techniques with the Inclusion of Distributed Generations and Unbalanced Loads to a Power Network by Therese Uzochukwuamaka Okeke.
Abstract: Owing to the frequent changes to power system networks in recent times, continuous studies are encouraged to ensure short, medium or long term planning & operation of any system is accurately resolved to avoid any shortcoming. This in essence, poses various challenges to power engineers as the most important and effective tool used to monitor their system stability continually encounters newer characteristics that were not previously taken into consideration, in this case, the distribution system. A well-articulated policy from various nations in the past decades, regarding global warming, depletion of conventional fuels and monopolization of rich fuels has greatly refurbished the conventional network we are accustomed to, especially at the distribution level. These policies paved way for renewable energy harnessing, which brought about advantages such as generating power at any location. While its advantages proved useful, it birthed nuisance to the engineers. Nowadays, engineers are concerned about the numerical techniques already in use for solving power flow issues as they now produce divergent solutions when used in these modernised networks.  This thesis will present and compare the various load flow techniques used, both the conventional methods and its variants, and also the recent techniques proposed. It will also present a new model recently proposed by a group of researchers that have reduced the complexity attached to modelling components of power systems.
Thesis Supervisors: Cristina González-Morán, Pablo Arboleya.
Erasmus Mundus Master Course in Sustainable Transportation and Electrical Power Systems at the University of Oviedo.

Abstract: This thesis develops a power reliability-based methodology to be used in a computer tool that assesses the selection of the most convenient power distributed-generation system in residential buildings. To do this a building power demand model is implemented by considering the dwellings’ energy consumption, the number of users per dwelling, the non-occupied periods of the inhabitants and the load’s usage pattern between others aspects. Some study cases are carried out under different scenarios to validate the proposed methodology by studying key reliability indexes that provide relevant information to infer the feasibility of the selected distributed generation. The attained results were very promising as they revealed for every case which were the most suitable power generation configurations to be employed.
Thesis Supervisor: Pablo Arboleya. Abstract: In this thesis, I developed a computer tool which is able to simulate the electrical energy generation of different generators, such as wind turbines, PV panels, fuel cells or micro turbines, for their employment in residential buildings for self-consumption. This involved the development of the mathematical models, as well as the estimation of some weather conditions such as wind profiles and solar radiation. In addition, the economic analysis, which consists on the comparison between the traditional energy purchase and self-consumption, has been also performed. This thesis is part of a project that also covers the demand modeling and the power reliability analysis of the system. The computer tool has been succesfully tested, by simulating different study cases, obtaining good representative results.