不同接地方式下配电网绝缘监察的灵敏性分析

依据零序电压幅值的绝缘监察是配电网接地故障识别的基本保障,中性点接地方式以及消弧线圈调节方式将影响高阻接地时的灵敏性。分析了不同接地方式配电网的零序电压随故障点过渡电阻及系统对地电容电流的变化规律,确定了不同接地方式配电网能够监察的最大过渡电阻(即绝缘监察的灵敏度)。结果表明,不接地系统灵敏度一般在2000?以上。预调谐式消弧线圈系统的灵敏度在2500?以上。随调谐式消弧线圈系统的灵敏度较小,一般在230~2000?之间。小电阻接地系统与投切了并联小电阻之后的消弧线圈接地系统的灵敏度最小,仅有数十欧姆。仿真和现场数据验证了分析的正确性。

Sensitivity analysis of insulation monitoring of distribution network under different grounding modes

Insulation monitoring based on zero-sequence voltage amplitude is the basic guarantee for grounding fault identification of distribution network.Neutral grounding method and the mode of arc-suppression coil adjustment will affect the sensitivity under high-resistance grounding fault.This paper analyzes the variation law of zero-sequence voltage with transition resistance and capacitance current of system under different grounding modes.The maximum transition resistance that can be monitored under different grounding modes is determined(i.e.the insulation monitoring sensitivity).The results show that the sensitivity of the ungrounded system is generally above 2000?.The sensitivity of arc-suppression coil grounded system with pre-adjustment mode is above 2500?.The sensitivity of the arc-suppression coil grounded system with instantaneous adjustment mode is low,which is generally between 230?and 2000?.The small resistance grounding system and the arc-suppression coil grounded system,after the input of small resistor,have the lowest sensitivity,which are only tens of ohms.Simulation and field data verify the correctness of the analysis.