预防电缆沟起火的小电流接地系统单相接地故障处理

为避免小电流接地系统单相接地故障引发的电缆沟起火事故，采用火灾动态仿真分析方法得到了接地故障电弧导致电缆沟引燃的时间与空间阈值。在此基础上阐述了预防电缆沟起火的综合治理措施。论述了兼具相控消弧线圈和预调式消弧线圈优点的相控预调式消弧线圈的实现方式及其实验测试数据。阐述了跨线相继接地故障的处理方法，包含以暂态量法为主的连续检测过程及以稳态量法为主的增补处理过程。给出了单相接地保护跳闸延时的整定依据及间断性接地故障的处理方法。针对城区和郊区配电线路分别论述了集中智能容错单相接地故障处理方法和基于合闸速断的分布智能单相接地故障处理方法。介绍了在陕西全省172座110 kV变电站供电区域范围内配电网的整体应用成效，表明所论述的技术措施的有效性。

Treatment of a single-phase grounding fault in a small current grounding system to prevent fire in a cable trench

To avoid a cable trench fire caused by a single-phase grounding fault in a small current grounding system, this paper uses a fire dynamic simulation analysis method to define the time and space threshold of cable trench ignition caused by the arc fault. Comprehensive control measures to prevent a cable trench fire are described. We discuss how the method is implemented and the test data of the phase-controlled pre-adjustment arc suppression coil. The advantages of both the phase-controlled arc suppression coil and the pre-adjustment arc suppression coil are described. This paper also describes the processing method for the cross-country earth fault, including a continuous detection process of transients and supplementary processing of the steady-state. The setting basis of single-phase grounding protection trip delay and the treatment method for an intermittent grounding fault are given. We discuss a centralized intelligent fault-tolerant single-phase grounding fault handling method and distributed intelligent single-phase grounding fault handling method based on closing and quick breaking respectively for urban and suburban distribution lines. The effectiveness of the technical measures is demonstrated by the overall application of the distribution network in the power supply area of 172 110kV substations in Shaanxi province.