Influence of the converter topology on fault mitigation in HVDC links

High-voltage DC (HVDC) transmission lines enable highly efficient transport of electric energy over long distances. The state-of-the-art topology for HVDC is still thyristor-based, with a tendency to employ self-commutated converters on the basis of IGBT devices. Here, several module topologies are employed or under discussion - with relevant influence on the mitigation of faults on the AC and DC side of the converter stations. In this paper fault mitigation options for HVDC are analyzed, comparing the most relevant converter topologies. Advantages and disadvantages are discussed with regard to the intended use and layout of the transmission line (point to point, multiterminal operation, overhead line, cable) and the number and relevance of faults and interruptions of transmission.