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The level of fault current increases as urban power grid expands in recent years. The traditional relay protection has difficulties in preventing the increased fault current in power grid. Magneto-biased superconducting fault current limiter (SFCL) is a novel technology with two-stage fault current limiting capability of reducing the level of fault current in the first half of the cycle and further in the second cycle. It consists of a double-split reactor, a non-inductive YBCO component, and a fast circuit breaker. Achieving its coordination with relay protection can reduce the reconstruction cost of power system and contribute to the promotion of SFCL. This paper analyzes the SFCL's operating mechanism at first. Then, a typical 10 kV IEEE 9-bus power system model including the magneto-biased SFCL is built to theoretically investigate the quench and current limiting characteristics and validate the feasibility of SFCL. Finally, a distance protection setting of a simplified 10 kV urban power grid is calculated and the influence of the introduction of the magneto-biased SFCL on the distance protection is quantified. The simulation results of single-phase short-circuit fault show that the zone I and zone II of distance protection can be properly activated and there is little impact on the distance protection of zone III. [ABSTRACT FROM AUTHOR]

With increasing demand of the power load and the development of the new energy resources, voltage-sourced converter-based high-voltage direct current (VSC-HVDC) transmission system has been widely utilized. However, its development is seriously limited due to short circuit. To address this, high-temperature superconducting direct current fault current limiter (DC-SFCL) is designed. In this paper, a novel topology of DC-SFCL is firstly presented along with its principle and mathematical model. Secondly, the thermoelectric model of its superconducting current-limiting unit (SCLU) is established. In addition, simulation of VSC-HVDC system containing this novel DC-SFCL topology is analyzed using Simulink software. Finally, experimental measurements are designed and conducted to verify the correctness of the theoretical model. [ABSTRACT FROM AUTHOR]