直流电源接地故障分级定位和隔离系统

直流电源系统是发电厂、变电站站用电源系统的重要组成部分,相当于发电厂、变电站的"心脏",保障了发电厂、变电站信号、控制、继电保护和事故照明等操作电源的供应。当变电站或发电厂的直流系统出现绝缘降低时,由绝缘监测装置产生报警信号,并让支路巡检装置启动选线工作。对于多级开关组成的系统,或者长的线路,进一步定位接地故障是比较麻烦的事情。"拉回路法"有可能导致保护和控制回路的重大事故,在一些地区已禁止采用;便携式直流接地故障探测仪的缺点是需要人工携带该装置逐条线路进行检测,一方面费时费力,且在电缆沟内无法逐段排查,另一方面存在带电作业的安全隐患。此外,传统的方式在排除接地故障之前,直流系统是"带病"运行的。文章提出的直流电源接地故障分级定位和隔离系统,可以较好地解决上述问题。

DC power supply system is very important in power plants and substations,it is equivalent to the"heart"of them and ensures the power supply for signals,controls,relay protections and emergency lighting.When the insulation level declines,the insulation detector will raise an alarm and let the slave detectors start inspection for each feeder.For those complicated DC power system with several levels of circuit breakers or with long cables,it is very difficult to localize the fault position."Feeder Switching Off Method"is not allowed in some regions as it may cause great power failure of protection and control equipment.Portable insulation detector has two defects,first,it takes a lot of time to inspect the whole cable and is impossible to do that in cable channels;second,it is not safe during inspection.In addition,the DC power supply system is operating"with disease",before the insulation fault is eliminated.This paper proposes a kind of localization and fault isolation system for DC power insulation fault,which can solve the above problems.