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Optimal operation of large electric power systems with HVDC interconnections

Goumagias Konstantinos

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Year 2019
Type of Item Diploma Work
Bibliographic Citation Konstantinos Goumagias, "Optimal operation of large electric power systems with HVDC interconnections", Diploma Work, School of Electrical and Computer Engineering, Technical University of Crete, Chania, Greece, 2019
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HVDC systems constitute a well-established technology used for massive electric power transmission over long distances. The term stands for High Voltage Direct Current, indicating the utilization of Direct Current (DC) as a substitute to Alternate Current (AC) in cases where the latter would prove highly problematic. The underwhelming performance of HVAC due to its high transmission losses and the significant operating cost make HVDC systems stand out in numerous applications. Moreover, in a world where the integration of renewables to the power grid becomes of utmost priority, HVDC is gradually gaining more ground in the collective attempt of the energy production decarbonisation.Under these circumstances, HVDC systems have become a growing trend for interconnecting regional or national electrical grids in order to form a larger unified network with enhanced stability and increased efficiency. Large interregional grids give to their individual subsystems the ability to conduct power transactions with the purpose of efficiently distributing the power generated across the wider system, which is the center of this work. The main aspect of this thesis is the optimization of large electric power systems, consisting of subsystems that do not possess information about the operating state of each other. The individual systems are interconnected by utilizing HVDC transmission lines, which allow them to exchange power in the attempt to achieve the global minimum operating cost. First, a reference is made to the properties, benefits and weaknesses of HVDC technology, along with its role in the today’s world. We present the fundamental technologies behind its operation while providing a glimpse of their characteristics. Additionally, we give an overview of the power flow (PF) and optimal power flow (OPF) analysis, in the context of Matpower, a simulation tool that was used extensively throughout our research. Then, we proceed to the thorough description of the algorithm that carries out the optimization, and the objective function that was based on the idea of the linearization of system operation cost. Finally, we showcase the performance of our approach alongside the baseline results by Matpower’s optimal power flow function. Experimental evaluation was performed for small and large system case studies, where our algorithm’s accuracy and performance were further examined.

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