THE ELECTRICAL PARAMETER CHARACTERISTICS OF VEGETATION IGNITION PROCESS CAUSED BY SINGLE-PHASE BREAKAGE FAULTS

Single-phase grounding faults in distribution networks account for a large proportion of total power system faults, and the vegetation combustion they trigger is a major cause of mountain fire accidents in transmission and distribution lines. Due to the complex interaction mechanism between fault arcs and surface vegetation, existing research lacks sufficient existing experimental data and unclear evolution mechanisms of the entire vegetation ignition process, leading to significant delays in fault detection and fire early warning. Therefore, this paper conducts discharge ignition tests of lOkV distribution network single-phase grounding faults on surface vegetation (typically shrub branches) to obtain the characteristics of the discharge ignition process and electrical parameter changes. Based on a lOkV distribution network single-phase grounding fault test platform, three-stage evolution characteristics of the entire discharge ignition process of vegetation are captured: Stage I discharge smoldering, Stage II arc migration, and Stage III combustion spread. The results show that due to their higher resistivity, shrub branches are less prone to arc breakdown, resulting in a later appearance of tiny arcs; meanwhile, shrub branches have higher moisture content and lower oil con-tent, and under the thermal effect of tiny arcs and leakage current, only surface carbonization, water evaporation, and other phenomena occur. If the risk of discharge smoldering is predicted in a timely manner at Stage I and effective measures are taken to handle the fault, the discharge ignition process can be prevented from developing to Stage II in a timely manner, providing data support for studying the mechanism of vegetation discharge ignition and its early warning methods under distribution network faults.