Comparison of conventional and improved two-level converter during AC faults

Vozikis, Dimitrios and Alsokhiry, Fahad and Alabdulwahab, Ahmed and Adam, Grain Philip; (2020) Comparison of conventional and improved two-level converter during AC faults. In: 2020 9th International Conference on Renewable Energy Research and Application (ICRERA). IEEE, GBR, pp. 352-358. ISBN 9781728173702 (

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An improved two-level converter (I2LC) is a practical compromise between the conventional two-level converter (C2LC) and modular multilevel converter (MMC), recently proposed for dc transmission system for relatively lower dc voltages and rated powers. The I2LC inherent the ac and dc fault behaviors of the MMC and relative simplicity of C2LC. Therefore, this paper presents a detailed quantitative comparison between the ac and dc responses of the C2LC and I2LC to symmetrical and asymmetrical ac faults. It has been showing that unlike the C2LC, the I2LC provides better controllability than the C2L at system level during asymmetrical ac faults, including two operational objectives simultaneously such as balanced output currents and ripple-free dc-link current. Index Terms—ac and dc faults, two-level converter, improved two-level converter, medium and high-voltage direct current (HVDC) transmission systems.