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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]

This document presents a comparative study of solid and thin-layers superconducting fault current limiter (SFCL) for electrical network transient stability improvement. Two applications of transient stability appraisal are presented in this article: the first shows the efficiency of the massive and thin-layers SFCL in series with a generator; the second uses SFCL installed in series with a transmission line. SFCL can only be used during the period from the fault occurrence to the fault clearing; the modeling and the effect of SFCL have been investigated to have higher benefits for the power system. In the present work, modification of the admittance matrix method is used for modeling of SFCL; critical clearing time (CCT) has been used as an index for evaluated transient stability. The results of the simulations showed the benefit of designing a superconducting current limiter from thin layers. These considerably improve not only the thermal stresses of the current limiter during the process of limiting the fault current by the significant decrease in temperature but also by its important contributions for the improvement of the transient stability of the electrical network. Thus, they can considerably extend the life of a second-generation superconducting current limiter. The modeling of the network tests will be made by PSAT under the MATLAB environment. [ABSTRACT FROM AUTHOR]

This paper presents a type of high temperature superconducting (HTS) cable, which is fabricated by winding the second generation (2G) HTS tapes on round former consisting of stranded stainless steel (SS) wires. It has the advantages of strong flexibility, high mechanical strength, and high engineering current density. With taking the resistivity of SS much larger than that of copper or aluminum, the cable has higher resistance and strength than the conventional HTS cable with former made from copper strands at condition of fault accident. After the configuration of the cable is designed in detail, the quenching resistance and fault current limiting are numerically analyzed. We fabricate a model cable and carry out the experiment of fault current. The experimental results show that the quenching resistance of this cable is much higher than the resistance of conventional underground XLPE cable and overhead conductor, which indicates that the proposed cable has a strong ability of fault current limiting and can be applicable in HTS devices with functions of fault current limiting such HTS cable, transformer, motor/generator, and current limiter. [ABSTRACT FROM AUTHOR]

When short-circuit fault occurs in a voltage source converter–based high-voltage direct current (VSC-HVDC) transmission system, the fault current curve is much more complex than conventional AC power grid. The high-voltage DC circuit breaker with large cut-off capacity is rather expensive; thus, some current limiting methods are proposed to limit the fault current. The superconducting fault current limiter (SFCL) is one of the promising devices for both AC and DC short-circuit current limiting application. The optimization criterion for SFCL applied in VSC-HVDC system is presented, and a four terminal VSC-HVDC system is adopted as an example. The short-circuit fault could be divided into condenser discharge and AC system feeding process, and the fault current curve is related to the time-varying RLC parameters of the grid. The thermal and resistance characteristics of the SFCL are analyzed, and the optimization method of the current limiting impedance and thermal characteristics of the SFCL is developed based on the time-varying fault current. Finally, the design of a 160-kV SFCL was completed based on the proposed method. [ABSTRACT FROM AUTHOR]

Superconducting fault current limiters are highly effective solutions to reduce and control excessive fault current which is inevitable in electric power systems. Resistive type superconducting fault current limiter (RSFCL) is used in parallel by multiple superconducting units, but there is a problem of uneven current distribution in parallel, which seriously affects its reliability and safety. In order to explore the problem of current sharing in parallel and find out the law of current distribution, a series of experiments are designed to verify it. Experimental research has found that whether in the steady state or the transient state, the more the superconducting units are connected in parallel, the smaller the current difference is, but it does not mean that the current sharing is better. This paper introduces a new evaluation model of current sharing, which evaluates the current sharing effect of different numbers of parallel situations in various states, and finds the law of current sharing, which provides a reference for application research of the subsequent. [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]

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]

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]

In the applications of high-temperature superconductors (HTS), the HTS tapes are usually exposed to the external magnetic field with different orientations. The critical current and AC loss are affected by both the field amplitude and field angles due to the anisotropy of HTS tapes. In this work, we first introduce the experimental system to measure the magnetization loss in HTS tapes based on the calibration-free method. Then, we present the magnetization loss results in 4.8-mm-wide AMSC wire, 4-mm-wide SuperPower wire, 4-mm-wide SuNam wire, and 10-mm-wide Fujikura wire in a perpendicular applied field at 77 K. The field amplitude is up to 100 mT, and the frequency varies from 44.2 to 87.1 Hz. We also present the magnetization loss in AMSC wire, SuperPower wire, SuNam wire, and Fujikura wire at different field angles. The field angle varies from 10 to 90 ∘ in 10 ∘ steps. The loss reduction with the decreasing of the field angle shows the anisotropic property of HTS tapes. We finally plot the measured magnetization loss of the samples as a function of the magnetic field amplitude normalized by the field angle to verify an empirical formula. [ABSTRACT FROM AUTHOR]

Overcurrent performance of high-temperature superconducting (HTS) coated conductor (CC) is one of the most crucial parameters for industrial applications, especially in superconducting fault current limiters (SFCLs). Thus, numerical study of overcurrent process becomes desirable in design of these superconducting devices. In this paper, a field-circuit combined model is introduced to study the overcurrent process of HTS CCs. This model is built by both MATLAB and COMSOL. Circuit parameters, electromagnetic, and temperature distributions are individually calculated by different software. Temperature ( T), magnetic intensity ( B), and generated heat ( Q) are used as real-time intermediate exchanging variables. Accuracy of this model is verified by short-fault experiments on straight HTS CC. Further applications, such as reclosing process and superconducting coils are both performed. Results obtained in this paper prove the validity of this model; this model can be helpful in future design of superconducting devices. [ABSTRACT FROM AUTHOR]

The global consumption of electricity is on the rise due to the industrial and population growth. The number of power generation and distribution facilities is increasing in order to meet the growing demand. Furthermore, the low impedance of power systems is causing a fault current that exceeds the capacity of the existing circuit breaker. In this paper, a method was suggested which limits the initial fault current by combining a superconducting fault current limiter (SFCL) with the existing flux-offset-type fault current limiter (FCL). Results showed that the initial fault current within a half cycle was limited by approximately 60%, while the fault current after a half cycle was limited by approximately 80 %. Overall, 99.8% of the fault current was limited, while the power burden on the SFCL was reduced by more than 50%. [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 paper presents a numerical (finite element) analysis of superconductor stability and current propagation under random variations of critical superconductor parameters. Instead of using singular (homogeneous) values, random variations potentially are appropriate to take into account any conductor inhomogeneity that can be considered as an obstacle to current propagation. Traditional assumptions like homogeneous current distribution, critical temperature, critical current density and critical magnetic fields are not justified in general; a local disturbance (for example, release of mechanical stress energy), if not immediately distributed by solid conduction, would generate a transient increase of local conductor temperature. Local critical current density and magnetic field then will be reduced, and current distribution will change. Disturbances may arise also from transport currents that locally exceed the critical current of the superconductor. Disturbances of all kinds may increase the conductor temperature above its critical value. A local analysis of all superconductor states thus is mandatory to safely avoid a quench. As an extension of standard stability models, also flux flow resistive states are taken into account. We will try to find a possibly existing correlation between current propagation and superconductor stability. Fault current limiting is discussed as a special case of current propagation. The analysis is applied to a bundle of high-temperature superconductor (HTSC) filaments. As will be shown, temperature profiles in a superconductor do not allow a clear distinction between Ohmic resistive or flux flow resistive fault current limiting. Though frequently made in the literature, this separation is highly questionable, because Ohmic resistive and flux flow resistive states may locally coexist, side by side, but are not very stable in the superconductor volume. [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]

In this paper, a 220-V resistive superconducting fault current limiter (SFCL) prototype is built and tested under different prospective fault currents, which vary from 0.8 to 7.4 kA. A 2D superconductor model is integrated into an experimental circuit model in COMSOL to simulate the performance of the SFCL prototype in the experimental system in fault tests. In the simulation, a new E- J relationship is proposed to enhance the convergence of calculation. Comparison between simulation results and experimental results shows that the proposed model performs well in simulating current limiting performance of SFCL in experimental system in case of fault. [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]

In view of the development of high-temperature superconducting materials, more applications on electric utility devices are used in the power industry. In this paper, a modified flux-coupling-type superconducting fault current limiter (SFCL) is suggested to mitigate the effect of DC short circuit in a voltage source converter-based high-voltage direct current (VSC-HVDC) system. The SFCL's structural principle is firstly presented. Then, considering that the SFCL is placed in series with a VSC-HVDC transmission line, its influence mechanism to the DC fault current's dynamic process is analyzed, and some brief discussions on the design of the SFCL are carried out. Further, the detailed model of a 100-kV-class VSC-HVDC system integrated with the SFCL is built in MATLAB/SIMULINK, and a simulation analysis is performed. From the demonstrated results, applying the SFCL can help to suppress the DC fault current, compensate the DC voltage sag, and maintain the power balance. Consequently, the VSC-HVDC system's robustness against the DC short circuit fault can be well enhanced. [ABSTRACT FROM AUTHOR]

BiPbSrCaCuO ( x = 0.0, 0.3, 0.4, and 0.5) textured materials have been prepared by the laser floating zone technique. The E − I curves showed and increase of the slope of the normal to superconducting transition with Pb addition. The best values have been obtained for the 0.4 Pb-doped samples, around 16 at 77 K. In spite of this improvement, Pb addition decreased J and T in all cases. On the other hand, electrical characterization at lower temperatures has led to an impressive raise in the 0.4 Pb-doped samples, reaching n values around 31, and J of about 3,000 A/cm , at 65 K. At the same time, the mechanical integrity of the vitreous precursor materials has been determined. All the obtained results clearly indicate that these precursors, when properly processed by the laser floating technique, are promising candidates for practical applications as current limiters. [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]

In this paper, a flux offset-type fault current limiter was proposed as a new means of reducing fault currents. The flux offset-type fault current limiter is a device that is integrated into the fault current technology, to which the flux offset principle of a transformer is applied, and is combined with a transformer and a fast switch. To secure the operation reliability of a flux offset-type fault current limiter, a simulation system was constructed to analyze its operation characteristics by generating a single line-to-ground fault and a triple line-to-line fault. According to the test results, the system performed stably without any impedance, because the primary and secondary winding fluxes of the transformer offset each other at normal times. However, when a fault current event occurred, because the fast switch was activated to limit the fault current by opening the secondary windings of the transfer within an average of 9.5 ms, which is shorter than the operation time of the existing electric circuit breakers by 3-5 cycles, the system is likely to perform protective coordination with circuit breakers in the future. In addition, the application of this current limiter could keep the fault current limit ratio to about 96 %. [ABSTRACT FROM AUTHOR]

A subcooled liquid nitrogen cooling system is known as the most promising method for developing a high-voltage superconducting apparatus, such as a superconducting fault current limiter, a superconducting transformer, and so on (Kang et al, IEEE Trans. Appl. Supercond. 18, (2), 628-631 2008). Gaseous nitrogen is injected into a superconducting magnet system to control the pressure and enhance the dielectric characteristics of a subcooled liquid nitrogen cooling system. In this case, the application of a solid insulating barrier between electrodes is regarded as an effective method to enhance the insufficient dielectric characteristics of gaseous nitrogen to develop a transmission superconducting apparatus. Dielectric experiments for a solid insulating barrier made of glass fiber-reinforced plastics (GFRP) in gaseous nitrogen are conducted under various pressures (0.1 ∼ 0.4 MPa), and the results are analyzed. A solid insulating barrier is installed between a rod to plane electrode system. The AC electrical breakdown characteristics according to the pressure of gaseous nitrogen and the position of a barrier between two electrodes are observed. [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]

This paper presents a saturated magnetic core superconducting current limiter (SCSFCL) operation simulation results using finite element technique. The superconducting current limiter uses BSCCO tape to produce magnetic core saturation to increase the device inductive reactance, during a short-circuit occurrence, thus limiting the short-circuit electric current. The electrical current limiter presents a limiting factor of 56 % of the prospective electrical fault current during 100 ms. A prototype of this SCSFCL is under construction to be tested in a superconducting laboratory. [ABSTRACT FROM AUTHOR]

The typical starting current for an asynchronous three-phase electric motor is in the range of five to ten times the rated current. To mitigate problems caused by this high current, various methods to start this type of motor exist. As an alternative method for starting up induction motors, a new starting current limitation method is proposed, which is based on using commercially available high-temperature superconductor tape. A prototype of the superconducting starting current limiter was constructed and tested with a 55-kW industrial induction motor, in a 440-V/60-Hz three-phase power grid. As the total starting time can be longer than the time the superconductor tape can support a high current, a shunt reactor receives the starting current after 80 ms to avoid damage to the tape. Performance evaluations of the superconducting limiter method were performed and were compared with a direct-on-line starter and an electronic soft starter. In addition to limiting the starting current, our method offers reduced current waveform distortion and lower harmonic pollution during startup. [ABSTRACT FROM AUTHOR]

There are many irreplaceable advantages of high temperature superconducting (HTS) fault current limiter, applying in electric utilities. It is expected to be able to solve excessive fault current problems and to enhance safety and stability of power systems. In this paper, the R and D of an improved bridge-type 10.5 kV three-phase superconducting fault current limiter (SFCL) was present. Each phase adopted a HTS coil with inductance of 6.2 mH. The three coils wound with 8,571 m Bi2223/Ag tapes totally. After installation at a 110 kV/10.5 kV substation in Hunan Province of China, the performances of the whole SFCL were tested, including a three-phase-to-ground short circuit experiment at the pre-setup short circuit point. And then, the SFCL was put into operations in the 10.5 kV power grids for more than 11000 h. About 3 years later, the SFCL was moved, reinstalled, and put into operation again since February 16 of 2011 at a 10.5-kV superconducting power substation located in Baiyin, Gansu Province of China. In this paper, the redesigned and manufactured cryostats with nonmagnetic stainless steel, tests, and long-term operations of the SFCL in 10.5 kV power grids were also described in detail. [ABSTRACT FROM AUTHOR]

A multi-physics finite element model of high-temperature superconductors (HTS) will be presented in this article. The electrical-thermal model is mainly based on Maxwell's equation and basic heat transfer equation to calculate the temperature propagation along the length of the superconducting tapes. According to the calculated temperature profile during quench, the surface thermal stress of the tape is obtained by a structural model. This model can be used to evaluate the degradation of tape performance due to the surface thermal stress, and the results can be used to minimize these effects in the SFCL system. The proposed model is used to investigate the uneven tape, the thickness of the copper layer and YBCO layer which is non-uniform. Methods of smoothing the degradation effect by adding auxiliary fixed points to the tape and changing the basic thickness of copper layer are discussed. [ABSTRACT FROM AUTHOR]

In a resistive superconducting fault current limiter (SFCL), the electrodynamic force among the YBCO tapes is enormous when experiencing a high short circuit current, which may cause deformation of tapes and damage of their electrical characteristics. The purpose of this paper is to investigate how much electrodynamic force the YBCO tapes can bear. In this paper, an electrodynamic force simulation model is built to simulate the force, which the two parallel tapes experience and their deformation when short-circuit currents of different value flow through. Then we conducted experiments to observe the deformation of the tapes when they are experiencing a short-circuit current and see if the volt-ampere characteristic of the tapes has a noticeable change after that. Combining the results of the simulation and the experiments, we can obtain the electrodynamic force that tapes can bear. The result can guide us to design the layout of the tapes in the SFCL in accordance with the required fault current level. [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]

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]

This paper presents a comparative study of resistive and inductive superconducting fault current limiter (SFCL) for power systems transient stability improvement. Two applications of transient stability assessment are presented in this paper: The first shows the efficiency of the resistive and inductive SFCL in series with a generator, the second uses SFCL installed in series with a transmission line. SFCL can just be operated during the period from the fault occurrence to the fault clearing; the modeling and the effect of SFCL has been investigated to have higher benefits for the power system. In the present work, modification of the admittance matrix method is used for modeling of SFCL; Critical Clearing Time (CCT) has been used as an index for evaluated transient stability. The transient stability is assessed by the criterion of relative rotor angles, using the Runge–Kutta method. The effectiveness of the proposed method is tested on the WSCC3 nine-bus system applied to the case of three-phase short circuit fault in one transmission line. A simulation and comparison are presented in this document. [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]

The original version of this article contains the following mistakes: On the second page 1st paragraph under heading “The Role of the Substrate Diffusivity” second and third sentences, 90 K, 300 cm2/s and 5 mm, should be replaced with 65 K, 100 cm2/s and 3 mm. [ABSTRACT FROM AUTHOR]