Fault Protection Scheme for Embedded Multiport Flexible Ac Interconnector

The soft open point (SOP) is proposed to solve the potential voltage violation and power flow congestion issues in the distribution network. Compared to the traditional back-to-back modular multilevel converter (BTB-MMC) based SOP, an embedded multiport flexible ac interconnector (eM-FACI) with smaller size, lighter weight was provided. However, due to its serial-shunt structure, the short-circuit current contributed by the healthy feeders will flow into the faulty one under fault conditions. The consequent overcurrent on the faulty feeder and voltage sags on healthy counterparts deteriorate the normal operation of the system. This paper proposes a hybrid fault current suppression scheme for the eM-FACI to limit the short-circuit current of the fault feeder and maintain the port voltage of the healthy feeders. The proposed scheme limits the current through using the current-limiting inductors and an active current suppression control strategy. The effectiveness of the proposed fault current suppression scheme is verified by MATLAB/Simulink.