消弧线圈并联小电阻的灵活接地方式

Flexible Grounding via Arc-suppression Coil and Low Resistance in Parallel

针对中性点经消弧线圈接地方式对永久性故障选线不够快速、准确,经小电阻接地方式无法区分故障类型的缺陷,结合消弧线圈接地方式供电可靠性高、小电阻接地方式可快速切断故障等优点,提出消弧线圈并联小电阻的灵活接地方式,其基本思想是正常运行和发生瞬时接地故障时投入消弧线圈,发生永久性接地故障时投切小电阻,实现中性点接地方式的灵活转换。介绍了消弧线圈并联小电阻灵活接地装置的组成、工作原理和小电阻的参数选取,并通过2个实际案例说明这种灵活接地方式可降低线路跳闸率,提高供电可靠性,适用于电缆线路和架空线路混合的城市配电网。

Aiming at defects of grounding mode of neutral point via arc-suppression coil being not rapid and correct enough for line selection for permanent fault while unable to distinguish fault types via low resistance,this paper proposes a flexible grounding mode via arc-suppression coil and low resistance in parallel by combining advantages such as high power supply re-liability of arc-suppression coil grounding and rapid switch-off for fault of low resistance grounding.The basic idea of this grounding mode is to input arc-suppression coil at the moment of normal running and instant grounding fault occurring while to switch low resistance when permanent fault occurs in order to realize flexible transform of neutral grounding mode.This paper introduces composition and working principle of the flexible grounding device and parameter selection for low resist-ance.By two practical cases,it proves that this flexible grounding mode is able to reduce line trip rate and improve power supply reliability which is suitable for city power distribution network mixing cable lines with overhead lines.