Dc-dc converters for HVDC heterogeneous interconnections
(English) High voltage direct current (HVDC) technologies have been used for bulk power transmission over long distances since the 1950s. These technologies have proven to be the most cost-efficient compared to the high voltage alternate current (HVAC) for some applications such as offshore power tr...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/689033 |
| Acceso en línea: | http://hdl.handle.net/10803/689033 https://dx.doi.org/10.5821/dissertation-2117-395073 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Enginyeria electrica 621.3 |
| Sumario: | (English) High voltage direct current (HVDC) technologies have been used for bulk power transmission over long distances since the 1950s. These technologies have proven to be the most cost-efficient compared to the high voltage alternate current (HVAC) for some applications such as offshore power transmission, connecting remote loads or generation, and the interconnection of non-synchronized grids. In recent years, the study of HVDC grids has been of interest in some research projects but, its development is still uncertain. The de grid can be planned beforehand or it can use the installed lines. But, from the installed HVDC projects, it can be identified different operating voltages, used technologies, and line topologies. There are two HVDC technologies: the line commutated converter (LCC), and the voltage source converter (\/SC). Four different line topologies are identified: asymmetric monopole, symmetric monopole, bipole, and rigid bipole. Developing a de grid interconnecting isolated lines with different characteristics cannot be possible without an intermediary device: the de-de converter. This thesis studies the de-de converters interconnecting HVDC lines with different characteristics. These converters can be seen as the equivalent of ac transformers in de applications because they are capable to adapt the voltage difference between two de systems. These converters are also capable to adapt the line topology and differenttechnologies. The power electronics required for these de-de converters provide increased control flexibility used to supply additional ancillary services that the classical transformers cannot furnish. Three de-de converter topologies are modeled and simulated for the interconnection between a bipole and a symmetric monopole. The front-to-front modular multi-level converter (F2F-MMC) is chosen as the reference because it represents state of-the-art technology. The second converter is the de-de MMC (de-MMC) because of the topological similarityto the MMC. Then, a third converter is proposed and studied as a result of this thesis, the asymmetric de-de converter (ADCC). A set of simulations are performed for multiple operating points and faults scenarios. Then, the converters are compared quantitatively and qualitatively. The results and analysis are used to conclude and bring some perspectives for future works. |
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