Modular multilevel converter (MMC) is the latest converter topology suitable for the transformerless applications in HVDC transmission. HVDC systems are required to remain connected during grid faults, provide grid support and completely decouple the healthy side from the faulty one. The MMC converter weak points are challenged by this particular condition and by these demands. This paper demonstrates the effect of negative and zero sequence current control in MMCHVDC during asymmetric grid faults. A current limitation strategy for MMC is derived and verified through simulations.
Proceedings of the Annual Conference of the Ieee Industrial Electronics Society, 2013, p. 2016-2021