Research on Saturated Iron-Core Superconductive Fault Current Limiters Applied in VSC-HVDC Systems

The high-voltage direct-current transmission based on voltage source converter (VSC-HVDC) system has pointed the way for the development of the smart grid, yet one challenge to be faced is that VSCs are vulnerable to dc short-circuit faults due to the huge discharge current of the dc-link capacitor. Therefore, the saturated iron-core superconductive fault current limiter (SI-SFCL) is introduced to limit the fault current to a relatively low level. The working principle and electrical properties of the SI-SFCL are discussed first. The relationship between the inductance and dc gird current of the SI-SFCL is deduced. The transient process of a short-circuit fault in the VSC-HVDC system with the SI-SFCL is studied. The maximum current and the drop velocity of dc rail voltage are presented according to the parameter of the SI-SFCL. The effectiveness of the SI-SFCL is proved by comparing fault currents and voltages of the VSC-HVDC system with and without it in PSPICE.