基于城市供电系统的电缆检测与单相接地故障定位一体化

摘要

我国大中城市供电系统多采用中性点经消弧线圈接地的系统供电,而且为了安全几乎100%采用电缆线路.针对此现状研究了发生单相接地时的电流特点和存在的问题,并结合城市电缆的工作环境,提出了利用附加低频信号技术实现城市供电系统保护、绝缘监测和故障选线的新方法.这种理论的主要特点是采用低频信号,通常选用12.5 Hz14.5 Hz等系列.其大小约是50 Hz的1/N(N＞1的整数).该方法不仅能够及时发现故障线路,也可以预防并提前发现由于绝缘缺陷引起的故障,可以极大地减少城市因电力系统引起的恶性事故,具有实际的应用价值.%First , the characters of power system with neutral unearthed were presented.Base on this , it andlyzed varied protections.In order to solve the problem in city power system,this paper proposed a new protection theory.The main characters of this new protection is low frequency , usually select 12.SHz, 14.5Hz, etc., The frequency of injection signal is about l/N times high as the 50Hz(N ＞ l).Base on this.it states the theory and characters of the protection.This methord can keep the city power systemsafety and find the cable insulation fauh ahead.