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In this article, a general scheme of a 40-kV/2-kA resistive type dc superconducting fault current limiter (SFCL) is suggested, which could be utilized to suppress the surge current caused by short-circuit faults in voltage-source-converter HVdc (VSC-HVdc) power grids. This dc SFCL is designed and fabricated with 6 coil modules in parallel and 4 in series. In order to investigate the current-limiting performance of the dc SFCL under the rapidly rising fault current, the SFCL is tested on the platform with a pulsed dc impact generator. Besides the property of current limitation, the current capacity, insulation and quench recovery performance of such SFCL are also tested. Results indicate that the critical current of SFCL is larger than 2050 A at 69 K, and the dc withstand voltage is larger than 74 kV in 2 h. During the 9-kV dc impact test, the short-circuit current could be limited to 8842 A, and the quench recovery time is less than 200 ms. [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]

As one of the most effective ways for the suppression and interruption of short-circuit current in voltage source converter based high-voltage direct current (VSC-HVdc) power systems, superconducting fault current limiter (SFCL) has received more and more attention, especially the resistive SFCL. However, when the resistive SFCL is in the current limiting state or overload operation, a large amount of bubbles will be generated on the surface of superconducting tape, thereby affecting the insulation performance of the SFCL. Experiments are performed by using a heater-built-in electrode system where bubbles are generated from the surface of the ground electrode. The test can simulate the actual working condition. The effect of bubbles on breakdown voltage of liquid nitrogen (LN2) is investigated under different types of voltage (negative lightning impulse, positive dc voltage, and composite voltage of negative lightning impulse and positive dc voltage) and different pressures. The results show that the breakdown voltage of LN2 decreases with the increase of the number of bubbles regardless the type of voltage, and elevating pressure is an effective way to improve the insulation strength of LN2. All the test data can be used as the theoretical basis for insulation design of resistive SFCL. [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]