35kV电阻接地系统接地故障分析与保护措施

Analysis on the Grounding Faults in 35 kV System with Neutral Resistance Grounded and Its Protective Measure

城市配电网电缆线路增多造成电网对地电容电流增大,需要系统中性点经小电阻接地。对两条35kV线路因单相接地后发展成多相接地故障而跳闸的事故,通过分析,发现该事故是由于35 kV中性点接地电阻因故障烧坏而长期与系统断开运行造成的。对此,提出了在35 kV系统中性点经电阻接地的变电站应装设35 kV母线零压保护的建议。

The increase of cable lines in urban distribution network increases the grounding capacitive current of the network and the neutral with small resistance grounded is needed. By the analysis on an interruption caused by a multi-phase grounding fault developed from two single-phase groundings of two 35 kV lines, it is found that due to the burning out of neutral grounding resistance and thus causing the neutral isolated from ground for a quite long period. The paper suggests that in the substation of 35 kV system neutral with resistance grounded, the zero voltage bus protection has to be equipped.