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The resistive-type superconducting fault current limiter (R-SFCL) is simple in configuration, near zero impedance at normal state, and can be quickly triggered by the fault current. So, it is a possible solution to suppress the fault current in the power grid. In this paper, the design and development of a 220-kV R-SFCL were reported. The core component of it is a module constructed by 128 bifilar coils. The bifilar coils are connected in series and parallel to form the module according to the application requirements. The bifilar coils are made of 12-mm-wide steel-stabilized 2G tapes, while 16 bifilar coils are connected in parallel to form a sub-module and 8 sub-modules are connected in series to form the module. For this fault current limiter, 10.75-km 2G tapes are used in total, and the resistance of the R-SFCL module is 4.5 Ω at 300 K. Besides, the half-size sub-module and the cryogenic insulation support (CIS) are developed and tested. [ABSTRACT FROM AUTHOR]

The resistivetype superconducting fault current limiter (R-SFCL) is simple in structure, near zero impedance at normal state and can be quickly triggered by the fault current. Thus, it is a possible solution to limit the fault current in the power grid. In this paper, we report the fabrication and test for an R-SFCL module The R-SFCL module consists of seven bifilar coils connected in parallel, which were wound with two parallel 2G tapes. A 5mm spacer was co-wound between adjacent turns to act as the highvoltage insulation. In the tests, we test the current distribution among the bifilar coils, and then simulated short-circuit tests were conducted on the module to obtain its performance under fault current surge. [ABSTRACT FROM AUTHOR]

Optimization of high-temperature superconductor (HTS) coated conductor for standalone superconductor fault current limiting (FCL) systems and for inherently fault current limiting cables is quite different. To minimize the amount of conductor, and so to lower cost, a high conductor critical current per unit width I is desirable to minimize the number of parallel conductors required to meet operating current requirements. In standalone systems, a high normal state resistivity and thin conductor are also desirable to minimize conductor length. But in FCL cables, conductor length is fixed by the application. Limits on I , resistivity, and thickness also come from the necessity to prevent local overheating during a fault or, in a cable, bubbling of liquid nitrogen which could precipitate a dielectric failure. A critical insight is that even for low-voltage faults, hot spots can arise in the conductor, and heating within these hot spots must also be controlled. A simple model is introduced to describe this phenomenon and estimate hot-spot heating. Tolerable hot-spot temperature rise in FCL cables is drastically less than in standalone FCLs. Implications for design of FCL cables are discussed and their viability for applications such as linking substations at the distribution level is demonstrated. [ABSTRACT FROM AUTHOR]

This study has assessed the performance of a resistive superconducting fault current limiter based on polycrystalline SmBaCuO (Sm-123) subjected to 750 short-circuit events with acting time 80 ms. Preliminary results indicate that polycrystalline Sm-123 cuprates can be used to build superconducting fault current limiters. The results of this study have demonstrated that after 616 short-circuit repetitions, the superconducting element was able to limit the fault current without degradation on low-level fault current density J < 3.7 kA/cm. [ABSTRACT FROM AUTHOR]

High-temperature superconducting (HTS) tapes currently used for the manufacture of resistive fault current limiters use metallic substrates upon which the HTS film is grown. Because the alloys used for these substrates, such as Hastelloy, have a rather high resistivity and low thermal conductivity, the HTS film must be protected by a more conducting metallic layer acting as a shunt to avoid burn out during a fault. This shunt layer limits severely the electric field generated during the fault to values smaller than 100 V/m. A long length of tape is then necessary to achieve the desired high voltage. We show here that by using a high thermal diffusivity dielectric substrate such as sapphire, it is possible to obtain much higher electric fields of up to several kilovolts per meter. [ABSTRACT FROM AUTHOR]

The saturated cores Fault Current Limiter (FCL) is one of the leading candidates for providing a commercial robust solution to the fault current problem. Basically, the saturated cores FCL offers low impedance during normal grid operation due to its saturated cores state and high impedance in fault events due to cores desaturation. We developed a method to obtain the nonlinear inductance curve L( I) of the saturated cores FCL from which we show that the dynamic inductance component, dL/ dt, contributes significantly to the FCL limiting capabilities. Specifically, we show that in some parts of the AC cycle, the dynamic inductance term dominates over the static inductance in contributing to the voltage drop across the device. We conclude that the design of saturated cores FCL should consider the dynamic inductance and calculate its contribution to the FCL voltage to benefit from better device performances. [ABSTRACT FROM AUTHOR]

Standard stability calculations following the Stekly, adiabatic or dynamic stability models apply purely solid thermal conduction mechanism, derive predictions under (quasi-) stationary and adiabatic conditions and assume ideal (mostly centrosymmetric) location of disturbances. Instead, the present paper takes into account also thermal radiative heat transfer in the superconducting solid, pool boiling, and considers the impact of random location and intensity of disturbances on the stability problem. The analysis is based on interplay between Monte Carlo radiative transfer calculations and a rigorous Finite Element method to calculate the resulting transient temperature field and stability functions. The combined Monte Carlo/Finite Element method is applied to 1G filament and 2G thin-film-coated high temperature superconductors. Results are strongly different from solutions achieved with standard, solely solid conduction thermal transport. It is not realistic, even in thin films, to assume uniform conductor temperature under transient disturbances. This may have significant consequences for design and simulation of performance of superconducting fault current limiters. There are doubts whether superconducting fault current limiters under any operation conditions could work in either pure flux flow or Ohmic resistive states. [ABSTRACT FROM AUTHOR]

Superconducting fault current limiter, SFCL, forms an important category of fault-current-limiting devices which limit the short-circuit current levels in electrical networks. Therefore, modeling its operation and anticipating its characteristic parameters are too important in its design and optimization process. In this paper a novel integrative method has been proposed which predicts, with a good accuracy, the behavior of inductive shield-type SFCL in different circumstances and approximates its main operational characteristics, as the through current, the inductance and the voltage-current characteristics. An algorithm is presented to calculate the exact distribution of magnetic flux and supercurrent density inside the superconductor bulk in different operational conditions using the well-known Bean model and for the first time the flux pinning effect has been taken into account in SFCL operation modeling. For estimation of flux density distribution outside the superconductor bulk, the FEM analysis has been utilized. An iterative method has been used, based on the numerical solution of differential equations, to calculate the instant value of the SFCL through-current and inductance. The proposed method of modeling has been studied on a specific design of shield-type SFCL and its through current in normal and fault conditions of a test circuit, variation of its inductance with time and its voltage-current characteristic are calculated theoretically. A prototype has been fabricated based on the studied SFCL design and has been tested experimentally. The comparison of the experimental and theoretical results shows that this modeling predicts the SFCL operation with a good accuracy. [ABSTRACT FROM AUTHOR]