小电阻接地系统接地故障综合保护方案

Comprehensive protection scheme for grounding fault in low resistance grounding system

针对现有小电阻接地系统接地保护选择性差、灵敏度低且高阻接地故障检测能力不足等问题,研究分析小电阻接地系统单相接地故障后零序电流特征,利用上下级纵向配合,提出基于零序过电流的多级接地保护和延时低定值高灵敏度接地保护,给出保护配置方案和各级保护整定原则。利用线路出口和中性线零序电流幅值横向比较,提出高阻接地故障选线方法。在典型小电阻接地配电网结构下的仿真验证了所提出接地故障综合保护方案的可行性与可靠性。

Because the existing grounding protection in low resistance grounding system had imcomplete protection configuration, poor selectivity, low sensitivity and insufficient ability to detect high-imedance grounding fault, the characteristics of zero sequence current while single-phase grounding fault occured in low resistance grounding system was analyzied. With the help of longitudinal cooperation between the upper and lower protections, the multistage grounding protection based on zero sequence current and the high sensitivity grounding protection based on low setting and time delay were proposed, and also the grounding protection configuration scheme and the setting principles at all levels were discussed. Fault line selection method was proposed for the high-impedance grounding fault using the lateral comparasion of the amplitudes of zero sequence currents between the outlet of each feeder and the neutral line. The feasibility and reliability of the proposed comprehensive protection scheme for grounding fault were verified by the simulation in a typical small resistance grounding distribution network.