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PhD. Thesis


Control strategies for enhanced dynamic response in hybrid AC/DC microgrids considering energy storage integration

Ángel Navarro Rodriguez

Abstract: This thesis is focused on the dynamic control of hybrid AC/DC microgrids by promoting new strategies for an improved dynamic response. The proposals in this work includes solutions for the control of grid-tied converters, the primary control of hybrid AC/DC microgrids with high penetration of power electronic converters and constant power loads, paying special attention to the role of interlinking converters, the compensation for the lack of inertia that characterize this kind of grids, and provide tools to address the delay and latency in frequency/phase estimation and the estimation of grid impedance, useful for its application in the converter/primary control, active power compensation, protections or power quality.

Thesis Supervisor: Pablo García Fernández



A hybrid solution for distributed energy storage for microgeneration in microgrids

Ramy Georgious Zaher

Abstract: Design of the electronic power and control system. Una solución híbrida de almacenamiento de energía de forma distribuída aplicada a microgeneración en microrredes eléctricas: Diseño del sistema electrónico de potencia y control.

Thesis Supervisor: Jorge García García.



Unified (AC/DC) power flow applied to railway networks

Manuel Coto García

Abstract: The thesis adds adds some new contributions to the unified alternating current/direct current (ac/dc) power-flow method that is applied to railway power supply systems. These contributions are mainly focused on the way that the unified power-flow problem is implemented. The authors propose a new technique based on graph theory to model the motion of the trains without varying the system topology and dimensions, as well as the solution vector. Furthermore, a new matrix formulation is developed to provide an easy way of setting out the problem. The combination of these techniques makes the unified ac/dc power flow easier to implement, and the comparison among different instants can directly be done, representing the major contribution of this paper. Finally, as a minor contribution, a new technique based on previous matrix formulation is developed to easily obtain all active and reactive power magnitudes in compact form.

Thesis Supervisors: Pablo Arboleya, Guzmán Díaz González.



Technical and Economical Analysis of Isolated Microgrids

Ahmed Mohamed Abd el Motaleb

Abstract: Several technical and economic analyses were conducted, re- garding microgrids, such as providing an insight about site matching suitability for droop-regulated microgrids supplied by wind generators, optimizing both energy production and economic performance for isolated microgrids supplied by wind energy and batteries and predicting some stability constraints for generation sources by small signal stability analysis.

Thesis Supervisors: Cristina González-Morán, Guzmán Díaz González.



Position Estimation and Control Alternatives for Magnetic Bearings Systems

Islam El-Sayed Mahmoud

Abstract: In many industrial applications, may energy is lost due to the friction among the fixed and moving parts. That friction limits the relative movement speed and the accuracy and also needs for periodic lubrication. However, high speed and precision are fundamental requisites in some applications. For these reasons and due to the need of a reduced energy consumption alternatives are needed. Systems based on magnetic bearings meet these specifications, removing the need of lubrication while allowing high speed and control precision. When applied to rotational movement, there are different topologies which can affect the control system. In this thesis the different existing topologies are compared. An analysis is carried out considering different constraints: size, load capability and electrical losses. Additionally, the distribution of the electromagnetic forces being developed by each topology are analysed as well as the effects of the rotor displacement over the electromagnetic force generation.

Thesis Supervisor: Pablo García, Fernando Briz del Blanco.


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