中性点非有效接地系统消弧装置试验研究

Experimental research on effect of arc-suppression device for neutral point non-effective grounding system

中性点非有效接地系统在电网中规模越来越大,当系统发生单相弧光接地故障时,由于电容电流过大而无法自行熄弧,因此会危及到电网设备的安全运行。针对宁夏电网中性点非有效接地系统消弧装置,对其运行状况、系统的电容电流、消弧装置的补偿电流以及残流进行了分析。分析结果表明:当电网出现单相接地故障时,消弧线圈由于存在本体电容电流测量不准、阻性分量、谐波分量等因素造成接地点的电流较大无法熄弧,而配置快速开关型消弧柜变电站则可以在20 ms内将故障点电流全部转移至变电站内的消弧柜,从而实现故障点彻底消弧。

At present,the application scale of neutral point non-effective grounding system is getting larger and larger in power grid.When the system happens single-phase arc grounding fault,the self arc-suppression will fail to work due to the overlarge capacitance current and threaten the operation safety of the power grid.Taking the arc-suppressing device of neutral point non-effective grounding system in Ningxia electric grid as a case,the system capacitive current,compensation current and residual current of arc-suppression device were analyzed.The analyzing results showed that when the single-phase arc grounding fault happens,the self arc-suppression fails to work due to the overlarge capacitance current caused by inaccurate capacity and current measurement,resistive component,harmonic component and other factors of the arc-suppressing coil.However,the arc-suppression cabinet of quick switch can transfer overall current at the fault point to arc-suppression arc in the substation in20ms and achieve thorough arc-suppression at the fault point.