Performance Evaluation Approach of Superconducting Fault Current Limiter in MMC-HVDC Transmission System

For a voltage-source-converter (VSC) based high voltage direct current (HVDC) system using modular multilevel converter (MMC) topology, it is vital to address the emergency DC fault current problem, and superconducting fault current limiter (SFCL) is a very serviceable and competitive solution. This paper proposes a performance evaluation approach for applying SFCL in MMC-HVDC transmission system. Firstly, according to different action stages of SFCL and DC circuit breaker (DCCB), the fault development process of the MMC-HVDC is elaborated. The fault current peak, dissipated energy of DCCB and fault clearance time are probed, and the critical limiting impedance is theoretically deduced. Then, three aspects of electrical stress, thermal stress and fault handling speed are specially considered, and a performance evaluation system with multiple indicators is built to assess SFCL functions. Using MATLAB, the performance assessment of a resistive SFCL and an inductive SFCL in a 320 kV/1.6 kA MMC-HVDC system is done. From comparative analyses, it is concluded that the resistive SFCL overall outperforms the inductive SFCL, and while the critical current-limiting resistance and inductance are gained. The suitability and feasibility of the proposed performance evaluation approach are validated.