中性点不接地系统两点异地接地距离保护探析

Discussion on Two-point Grounding Distance Protection in Neutral Non-grounding System

分析了中性点不接地系统发生异地两点接地故障时,相间距离和接地距离保护动作行为,结果表明两种距离保护均可能出现误动现象。为防止误动,提出了设置零序启动元件、零序闭锁元件及故障相电压与被保护线路故障相电压降比值的新判据,判据简单、可靠。

This paper analyzes the protective action of inter phase distance and grounding distance when two-point grounding fault in different spots occurs in neutral non-grounding system.The results show that maloperation may happen in both of distance protection.In order to prevent the maloperation,a new criterion is put forward by setting up zero sequence starting and blocking element and reducing voltage ratio between fault and protected lines phase voltage.This criterion is simple and reliable.