A study on S/N transition type and DC reactor type fault current limfter.

本文研究了利用高温超导线圈与变压器二次绕组通过二极管桥接的直流电抗器型和直流S/N过渡型故障限流器（FCL）。高温超导体优选应用于直流电抗器或S/N过渡型故障限流器，其中限流元件可在低压和直流两种情况下工作。此外，该装置的特点是在三相电力系统中只需要一个限流元件。此外，它还具有两种方式之一的故障限流中断（FCLI）功能；通过阻断晶闸管的闸极脉冲，在施加于桥极或闸极的偏置电流的帮助下自动中断故障电流。直流混合式三相故障限流断流器也是可行的，它是由一个高温超导电抗器和一个S/N过渡元件组成的折衷装置，设置在电抗器内，彼此串联。通过实验和分析验证了上述三种器件的故障限流中断性能，并对其特性进行了比较。很明显，每个线圈体积的中心磁场在线圈宽高比提供最小线圈体积时是最大的。组装导体需要建立防止不均匀电流的装置。利用间相反应器设计了一种使各链电流相等的方法，并通过实验验证了该方法的有效性。通过以上研究，明确了实现S/N过渡型和直流电抗器型故障限流器的研发目标。

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.