Numerical And Experimental Studies On Switch Behaviors Of Superconducting Fault Current Limiters Based On Au/YBCO Thin Films

The resistive-type superconducting fault current limiter (SFCL) is one of most attractive device for power failure protection due to its fault detection, self-triggered, rapid switching operation, and self-recovery. In the past decade, a range of different superconducting materials have been demonstrated to be the current limiting element of resistive type SFCLs including BSCCO tapes, MgB2wires, YBCO bulks, thin films and YBCO coated conductors. Among these superconducting materials the high-temperature superconducting YBCO thin films is promising candidate using for resistive-type SFCL. Because the SFCL composed of thin film has better performance on its compactness, rapid switching operation, and recovery, comparing with other types of superconducting materials. Its major drawback has been its high cost due to the high cost of large-area YBCO films on sapphire substrates. The thin-film SFCL, that are always installed in low or middle-high voltage grid, would have gained significant improvement, until cost reduction of thin-film SFCLs is strongly dropped for high voltage class transmission line.This paper introduces a new superconducting fault current limiter based on double-sided thin film, in which superconducting layers YBCO are grown on both sides of substrate. When both sides of superconducting YBCO thin film operates fault current simultaneously, this configuration will significantly compact the SFCLs system. Meanwhile, the thermal and electromagnetic circumstances in double-sided configuration become complicated. For validating the feasibility of double-sided YBCO thin films applied to SFCL, two2kVA double-sided thin film SFCL elements were fabricated. The quench behaviors of double-sided configuration were mainly analyzed by experimental and numerical method.In this work the AC loss of double-sided thin film is firstly calculated by using the H-formulation. The numerical results have demonstrated that the anti-inductive configuration of double-sided thin film obtained lower AC losses than traditional thin film in normal current range. From the over-current experimental measurement, it has been shown that the double-sided thin film SFCLs have unique performances on thermal stability, quench characteristics and recovery behaviors. The presented work allow to estimate the full operation properties of double-sided thin film, and it can be concluded that the double-sided thin film SFCL of operation properties is significant improved due to its double-sided configuration. This configuration is also appropriate for high voltage and large current prototype design, when patterning of double-sided thin film SFCL is optimized, or the double-sided thin film operates fault current with transformer type of SFCL.