LCC and MMC dynamic interactions in subsynchronous domain
University of Aberdeen, 2021
Online
Hochschulschrift
Zugriff:
Plans for future power systems indicate expansion of DC systems including application of HVDC transmission. This may lead to new hybrid AC-DC systems where two or more HVDC links of different technologies are connected to the same AC grid, and this raises concerns of new stability issues. Such scenario is expected in the North French topology which is used as the test system. There is an old 2 GW HVDC link (IFA2000) based on the traditional LCC, and experimental studies showed that it may destabilize the dominant 6.3 Hz torsional mode of a nearby nuclear generator (Gravelines plant). This is a well-documented phenomenon known as the subsynchronous torsional interactions (SSTI). It is studied in more depth, using analytical models and eigenvalue methods, to understand the influence of various key parameters and HVDC controller gains. Then, a study is conducted on the HVDC link based on the emerging MMC. It represents the new 1 GW French system Eleclink, and detailed representation of MMC and frequency-dependent DC cable in state-space enable analysis of the new systems. The results show that it may also introduce a significant risk of SSTI. This is contrary to previous studies which mostly consider simplified models representing early two-level VSC topologies. The Eleclink system is being installed in close proximity of the IFA2000 system (2020). A systematic comparison of dynamic stability limits is conducted between the point-to-point systems and the dual-infeed topology (both MMC and LCC) analyzing adverse interactions between the fast HVDC controls and the weak AC grid. The study shows that MMC HVDC can operate at the weakest AC grids and that it may improve stability of LCC HVDC. However, it may also deteriorate the risk of SSTI. Lastly, a subsynchronous damping controller is developed on MMC which can successfully mitigate all the identified SSTI.
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LCC and MMC dynamic interactions in subsynchronous domain
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Autor/in / Beteiligte Person: | Kovacevic, Stefan ; Jovcic, Dragan ; Aphale, Sumeet S. |
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Veröffentlichung: | University of Aberdeen, 2021 |
Medientyp: | Hochschulschrift |
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