摘要
小电阻接地配电网发生配电线路断线故障时,如果断线未能掉落在良好导电介质上,常规保护会因检测高阻接地能力的限制而达不到动作条件,因此无法及时切除,这导致故障长时间存在,留下危害系统可靠运行及人身安全的隐患。为了解决这个问题,分析了小电阻接地系统发生断线故障时的电流、电压特征,提出了以负序正序电流比例特征为主要判据,以电流限值条件和零序电压限值条件为辅助判据的断线保护。该保护采用配电网线路保护安装处的电压、电流量信息,易于实施,能够准确识别单相及两相断线故障并定位至故障本级线路,及时切除故障,保证系统的可靠运行以及人身的安全。
When a disconnection fault occurs at a distribution line in the low resistance grounding system,if the break line fails to fall onto a good conductive medium,the traditional relay cannot act because of the restrict of its high-impedance fault detection ability.As a result,the disconnection fault cannot be isolated in time.This causes the fault to exist for a long time,leaving hidden danger that endanger the reliable operation of the system and personal safety.To solve the problem,in this paper,the current and voltage characteristics of the low resistance grounding system in the case of disconnection fault are analyzed,and a breaking protection is raised.The feature of the ratio of the negative-sequence current against the positivesequence current is used as the main act criterion,and the value restrict of the max load current and the zero-sequence voltage are used as auxiliary criterion for the breaking protection.The protection only adopts the voltage and current quantity information at the installation spot,which is easy to implement.With the protection,the single-phase or two-phase disconnection fault can be identified correctly and located at the exact section,so the disconnection fault can be isolated in time,to ensure the reliable operation of the power grid and the personal safety.
作者
董凯达
蔡燕春
金震
DONG Kaida;CAI Yanchun;JIN Zhen(NR Electric Co.,Ltd.,Nanjing 211102,China;Guangzhou Power Supply Bureau Co.,Ltd.,Guangzhou 510620,China)
出处
《供用电》
2018年第8期14-20,共7页
Distribution & Utilization
基金
广州供电局有限公司科技项目(GZHKJ00000020)~~
关键词
小电阻接地系统
断线故障
断线保护
零序电压
负序电流
高阻接地故障
low resistance grounding system
disconnection fault
breaking protection
zero-sequence voltage
negativesequence current
high impedance grounding fault
