基于介质击穿原理的配电线路高阻接地故障精确建模

配电线路负荷率快速增加和电缆线路的广泛应用使得配电网中性点有效接地方式得到越来越多的应用。中性点有效接地配电线路受送电走廊、自然环境等因素影响,容易发生弧光高阻接地故障;此类故障电流幅值小,保护难以检测跳闸,很少能获取到现场录波数据;而人工接地试验成本高,难以频繁使用,因此挖掘有限的试验数据,实现弧光高阻接地模型的精确建模尤为重要。文中在详细分析基于热平衡原理的电弧模型机理的基础上,指出了该类模型不完全适用于开放空间,以及弱故障电流的高阻弧光接地故障。针对以上问题,文中基于固体介质电击穿原理,提出并建立了配电线路高阻接地故障点非线性电阻模型,理论分析及现场试验数据验证了模型的准确性;为后续的高阻接地故障检测算法研究奠定了理论基础。

High-impedance Fault Modeling Based on Solid Dielectric Electrical Breakdown Theory

The rapid increase of distribution feeder loading and the wider application of cables requires more frequent usage of effective neutral point grounding. High impedance faults (HIFs) often occur in effectively grounded distribution systems. They exhibit limited fault current which can be too small to be identified by conventional overcurrent relays. HIFs data is always beyond reach due to the poor action of existing relays; therefore, artificial fault experiment becomes a main approach to obtain fault data. However, the experiment is costly and limited to several fault surfaces. Modeling study provides an economical and flexible way for HIFs detection and provides better understanding of HIFs. Existing HIF models are mostly associated with arc, and are not always suitable for small current and open air HIFs. Several existing HIF models are analyzed in detail. Based on the solid dielectric electrical breakdown theory, a nonlinear fault model is proposed. The model is verified by artificial experiment data.