This thesis studies the technical-economic impact of the possible development of a direct current supergrid. The development of VSC (Voltage Source Converter) technology for high voltage direct current (HVDC) networks, allows to achieve multi-terminal and meshed topologies, providing alternative ways to electric power in case there is any type of contingency. This is especially relevant in order to be able to incorporate the entire offshore wind energy from the North Sea into the European system in a reliable manner. In addition, it is also possible to build corridors in HVDC on land to increase the interconnection capacity between different zones. However, before developing this supergrid, it is necessary to evaluate its impact, both from a technical and an economic point of view. This thesis proposes two models of Optimal Power Flow (OPF) to optimize the generation dispatch taking into account the network constraints (both AC and DC), and by considering a detailed modeling of the converters. The first model is a non-linear model (NLP-OPF) that represents the equations in a very precise way and that can serve as a benchmark model. The second model is a model where the whole set of equations is linearized (LP-OPF), and that makes it possible to apply it to realistic size problems as shown in the application case. One of the results of the thesis is that depending on the methodology followed to model the losses of the converters, the results of the OPF can vary substantially. Regarding the application of the LP-OPF, the example case studied in this thesis is a scenario of the European system in year 2030 that has been elaborated from information recapitulated in the context of the European project Best-Paths, where the impact that the development of a network in the North Sea to increase the installed wind power up to 45 GW is assessed. Finally, the thesis also presents a review of what are the most promising technologies to improve the transmission system (both AC and DC), and presents a discussion of the technical, economic and regulatory barriers that may prevent from its future development.
Universidad Pontificia Comillas. Madrid (España)
15 February 2019
Q. Zhao (2019), Technical and economic impact of the deployment of a VSC-MTDC supergrid with large-scale penetration of offshore wind. Universidad Pontificia Comillas. Madrid (Spain).