小电流接地系统单相接地综合电弧模型与选线方法的研究

Research on single phase grounding arc model and line selection for neutral ineffectively grounding system

在小电流接地系统中,发生单相接地故障时,电弧故障会经常产生。现有用于模拟电网的电弧模型大都是通过开关来实现,与实际的电弧接地有一定的差距。将Cassie电弧模型和Mayer电弧模型结合起来,使其更符合实际电弧接地,并运用到10 k V模拟电网中。在EMTP中,对中性点不接地电网、经消弧线圈接地,经高阻接地,电弧发生在不同合闸角,不同馈线时的情况进行了大量仿真。最后在Matlab中,用小波相关分析法进行选线。结果表明,该方法适用于大部分电弧故障,但对于电压过零点附近发生的电弧故障有一定的局限性。

When a single phase grounding fault happened in neutral ineffectively grounding system, arc fault usually generated. Most of the existing arc models for the electric network are realized via the switch, which has a certain gap with the actual arc grounding. Firstly, this paper combines Cassie arc model with Mayer arc model to make it more in line with the actual arc grounding, and applies it to 10 k V simulation power grid. Then, a large number of simulations on the electric arc occurring in different closing phase angles and different feeders are done with EMTP in neutral point ungrounded power grid, power grid of the neutral point connected with arc suppression coil and neutral point via high resistance grounding network. Finally, the method of wavelet correlation analysis is used to select the fault line in Matlab. The results show that the method proposed can apply to most arc grounding faults, but it has some limitations for the arc fault in the vicinity of zero points of voltage.