An adaptive‐impedance fault current limiter for accelerating fault current suppression in MMC‐HVDC systems

DC fault clearance is one of the critical issues for modular-multilevel-converter-based high voltage direct current (MMC-HVDC) systems. Employing a hybrid circuit breaker (H-DCCB) to isolate faulty line typical method achieve fast clearance. However, H-DCCB has interrupt and absorb energy up tens megawatts in several milliseconds. Through theoretical analysis interruption process using H-DCCB, reducing equivalent inductance during falling stage recommended accelerate suppression H-DCCBs. This paper proposes novel adaptive-impedance limiter (AFCL), which contains two coupled reactors an absorption branch (EAB). The proposed AFCL can automatically limit rising works as reactor with fixed through two-state model analysis. Meanwhile, contributes accelerating decline by adaptively discharge circuit. Consequently, time absorbed are reduced. Simulation case studies hardware experiments carried out verify performance practicality AFCL.