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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]

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]

The application of resistive-type superconducting fault current limiters (RSFCLs) in electrical networks is very attractive due to their relative compactness, light weight, and good performance. However, this technology still has drawbacks: asymmetrical quench, uncertain limiting velocity, passive action and incapability of enlarging capacity. Here, we present an active quenching technique which can potentially solve these problems. The quenching process is triggered using high-frequency (HF) AC fields, which are generated by two coupled copper coils attached on both sides of the YBCO sample. Our experiments show that this approach is effective in guaranteeing uniform quench and therefore is expected to be able to significantly extend the service life of the device. Moreover, the quench speed can be considerably increased by the HF field. We find that the performance of acceleration is positively correlated to the transport current, intensity and frequency of the AC field. In addition, a DC magnetic field is added around the sample holder simultaneously with the AC field, to study the field-angular-frequency dependence of the quench time t(BACfACBDC휃DC). Experimental results prove that the DC magnetic field can cooperate with the HF AC field to accelerate quench, which means better performance can be produced with lower costs with the two fields acting together. In all, this technique showed outstanding performance regarding quench acceleration and tape protection. We believe the HF-assisted quenching technology has a promising future in current-limiting devices and hope our findings could be helpful for its potential applications. [ABSTRACT FROM AUTHOR]

The resistive-type superconducting fault current limiters (RSFCL) prototypes using YBCO-coated conductors have shown current limitation for medium voltage class applications for acting time up to 80 ms. By connecting an air-core reactor in parallel with the RSFCL, thus making an hybrid current limiter, one can extend the acting time for up to 1 s. In this work, we report the performance of a hybrid current limiter subjected to an AC peak fault current of 2 kA during 1 s for which within the first 80 ms the SFCL limits the current concurrently with the air-core reactor, and for the remaining 920 ms, only the air-core reactor limits the current. In order to evaluate the actual conditions for subsequent reconnection of RSFCL to the power grid, the hybrid fault current limiter was tested varying the time interval for recovery from 900 ms and 1.2 s, followed again by the concurrent operation of the hybrid limiter during 1 s (SFCL during 80 ms). From this evaluation test, the recovery time can be measured and compared using the voltage peak generated in superconducting module from the first and second fault test. The recovery time was also determined through the pulsed current method (PCM) on short-length sample test. The results showed that the fault current was limited from 1.9 kA down to 514 A after 1 cycle of 60 Hz frequency, with recovery time lower than 1.2 s for two subsequent fault current tests. [ABSTRACT FROM AUTHOR]

Superconducting fault current limiter (SFCL) has become one of the most ideal current limiting devices to solve the problem of increasing short-circuit current in high-voltage power grid. This paper presents a resistive-type SFCL model developed using simulation software PSCAD/EMTDC. After being verified by finite-element model and experimental results, the model is used to study the impact of SFCLs on the power grid and the co-ordination between SFCL and relay protections in 10 kV distribution network. A series of simulations are carried out to find appropriate parameters of SFCL model to cooperate with relay protection devices. The final result in this paper could provide important quantitative basis of parameters for SFCL to be applied in a real power system. [ABSTRACT FROM AUTHOR]

Coated conductors are very promising for the design of a novel and efficient superconducting fault-current limiter (SFCL). The thermal and electrical behaviors of this type of SFCL in the presence of over-critical currents need to be investigated in detail to master its performance in a power grid. In this paper, an Electrothermal Model of a Coated Conductor (ETMCC), not simulated in the literature, is implemented and introduced in the library of MATLAB software. An algorithm to solve the differential equations characterizing the superconducting material is developed using the Runge-Kutta method. In this context the ETMCC under over-critical current is performed. Different dimensions and substrate configurations of the sandwich layers are considered. In order to improve the high-temperature superconductor (HTS)-FCL design, the influence of the substrate and shunted layers (using different materials) on the thermal stability is investigated. The simulation results are generalized, thus allowing us to determine the current threshold to achieve thermal stability of the HTS-FCL at any point of the coated conductor. [ABSTRACT FROM AUTHOR]