| Research Abstract |
The purpose of this work is to study a dc reactor type as well as a dc S/N transition type fault current limiter (FCL) using high temperature superconducting(HTS) coil, which is connected with the secondary winding of a transformer through a diode bridge.
The high temperature superconductors are preferably applied to the dc reactor or the S/N transition type fault current limiters, where a current limiting element can be operated at both low voltage and dc current. In addition, it features that this device requires only one current limiting element in three-phase power system. Further, it has a function of fault current limiting interruption(FCLI) in one of two ways ; automatic interruption of a fault current with the assistance of a bias current applied to the bridge or gate interruption by blocking thyristor's gate pulses.
A dc hybrid three-phase fault current limiting interrupter is also feasible as a compromised device composed of an HTS reactor and an S/N transition element, set up within the reactor, connected in series each other.
The performances of a fault current limiting interruption as for above three devices were confirmed both experimentally and analytically and their characteristics were compared.
It was made clear that the central magnetic field per coil volume is maximal at the coil aspect ratio providing the minimum coil volume. An establishment of the unequal current prevention is being required for assembled conductors. A method, which makes the current flow equal in each strand, is devised by means of interphase reactors, and its effectiveness was confirmed experimentally.
The target of research and development to realize S/N transition type and dc reactor type fault current limiter was made clear by the above researches.
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