DC pole-to-pole short-circuit behavior analysis of modular multilevel converter

This paper presents the behavior analysis of modular multilevel converter under DC pole-to-pole short-circuit fault, which is an important issue in fault management, electrical system design and MMC based power system protection and control. F irstly, the transient behavior is analyzed and the conduction overlapping angle γ is def ined. Secondly, seven possible short-circuit current paths induced by different γ values are identif ied, and the corresponding engineering short-circuit current calculation methods for both AC and DC sides are proposed. And then, the inf luences of impedance distribution factor k and equivalent short-circuit resistance RSC on short-circuit currents are elaborated. F inally, case study is used to verify the effectiveness of the proposed analysis methods.