恶劣地质环境下接地工程分流系数的评估方法研究

Study on the Evaluation Method of Division Factor of Grounding Engineering in Adverse Geological Environment

摘要: 恶劣地质环境下接地工程存在接地电阻偏高的问题，在故障情况下容易导致过高的地电位升高，危及系统的安全运行和人身安全。目前电力系统接地短路时故障电流分布和分流系数的计算往往只局限于单回架空线路或地下电缆的简单情况，且大多数情况下没有考虑非故障相的耦合作用，所建模型也没有考虑变压器的影响。针对这一问题，首先从理论上推导了入地短路电流理论模型，并根据故障位置的不同区分不同情况。其次，基于EMTP电磁暂态程序提出了入地电流简化计算方案，并运用在某恶劣地质环境水电站的案例实现了论文方法的应用。结果表明，入地短路电流是指构成接地网–大地回路进而引起接地网地电位升高的那部分短路电流，计算需要考虑站内短路和站外短路，以及单相接地短路故障和两相接地短路故障共四种情况下可能出现的最大入地短路故障电流。论文方法有助于快速准确进行入地短路电流计算，为准确的接地参数计算提供了有效的参考。

Abstract: There is a problem of high grounding resistance in the grounding engineering under the harsh geological environment, which is easy to lead to high ground potential in the case of fault, endan-gering the safe operation of the system and personal safety. At present, the calculation of fault current distribution and shunt coefficient is usually limited to the simple case of single circuit overhead line or underground cable, and the coupling effect of non fault phase is not considered in most cases, and the influence of transformer is not considered in the model. To solve this problem, the theoretical model of short-circuit current to ground is deduced theoretically, and different situations are distinguished according to different fault locations. Secondly, based on EMTP electromagnetic transient program, a simplified calculation scheme of ground current is proposed, and the method is applied to a hydropower station with adverse geological environment. The results show that the grounding short-circuit current refers to the part of the short-circuit current which constitutes the grounding grid earth circuit and then causes the grounding grid ground potential to rise. The calculation needs to consider the maximum grounding short-circuit fault current that may occur in four cases, namely, the short-circuit inside the station, the short-circuit outside the station, the single-phase grounding short-circuit fault and the two-phase grounding short-circuit fault. This method is helpful to calculate the short-circuit current quickly and accurately, and provides an effective reference for accurate calculation of grounding parameters.