Investigation of the Evolution Mechanism and Multiphysics Coupling in Tree‐Contact Single‐Phase‐to‐Ground Fault

Tree‐contact single‐phase‐to‐ground fault (TSF) is a common and hazardous type of failure in distribution networks. TSF is likely to occur when overhead conductors contact moist tree branches, potentially leading to insulation breakdown, posing serious threats to grid safety. This study investigates the fault evolution mechanism of TSF by establishing a multiphysics coupled simulation model incorporating electric, thermal and fluid fields, aiming to reveal the characteristics of moisture migration and heat accumulation within the tree. To validate the model, a TSF simulation experiment was designed and implemented. Surface temperature data were collected using an infrared thermal imaging camera and compared with simulation results. The observed consistency in the temperature rise trends between experimental and simulated data confirms the accuracy and reliability of the model in capturing the real discharge process. The results reveal that during discharge, electric current tends to flow along low‐resistance moisture‐rich pathways, where local current density accumulation intensifies Joule heating. This thermal effect, in turn, drives further moisture migration, forming a positive feedback loop that accelerates fault progression. The findings provide theoretical insight and visualisation tools for understanding TSF mechanisms, offering a basis for fault identification and monitoring.