Converter non‐blocking DC fault ride‐through and system fast restoration arrangements in R‐L SFCL‐equipped MMC‐M2TDC system

Abstract

Abstract Equipping a DC‐type superconducting fault current limiter (SFCL) in a modular multilevel converter‐based multi‐terminal DC (MMC‐M2TDC) system has the potential to reorganize the protection control arrangements during the DC‐side short‐circuit fault. This paper introduces the converter non‐blocking operation and system fast restoration control of the SFCL MMC‐M2TDC with the DC‐side bipolar fault condition, as well as their feasibility verifications. Considering the characteristics of overdamping oscillation of DC voltage and the additional impedance effect of the new resistor‐inductor SFCL (R‐L SFCL), the unfaulty converter non‐blocking protection enables faulty segment isolation and DC fault ride through without unwanted active power interruption. The restoration control for smooth reconnection and fast recovery of the off‐grid converter station ensures the DC voltage rebuilding process and reduces the required period. To validate the above arrangements, the simulation is conducted upon the PSCAD/EMTDC corresponding to the three‐terminal R‐L SFCL MMC‐M2TDC system. Finally, the research routes for novel superconducting coil design, SFCL scheme design, and multi‐device cooperative strategy are discussed, all of which contribute to promoting the high‐quality development of SFCL in MMC‐M2TDC scenarios.

Keywords

• converter reconnection
• DC‐side bipolar short‐circuit fault
• fast restoration
• faulty converter non‐blocking control
• modular multilevel converter‐based multi‐terminal DC
• Nanao project