Quantitative criteria of considering AC infeed in DC fault assessment of modular multilevel converters

An accurate and efficient DC fault current assessment of modular multilevel converters (MMCs) is critical for designs protection. The state-of-the-art often ignores the impact AC infeed in without MMC blocking. However, whether needs to be considered or not a controversial problem. This paper proposes quantitative criteria determine necessity considering assessment. method based on premise that blocking has occurred. Based average model MMC, contribution from side quantified under different control schemes. are established by contributing ratio over total current. obtained only rely system parameters, which enable designers identify ignoring effectiveness proposed validated two case studies results reveal submodule (SM) capacitance number SMs have large contribution.