Modelling abnormal temperature increases on composite insulators and influencing factors

In recent years, abnormal hot spots of composite insulators on overhead lines have been frequently observed, seriously affecting the reliability of transmission lines and the system security of the power network. Once hot spots are detected, the strategy of asset management is to crudely replace the insulator with very limited techniques to further verify the problematic ones, causing significant waste of manpower and material. This study first investigates the dielectric properties and temperature characteristics of abnormal heating composite insulators. Then, a simulation model is established to analyze the thermal fields of composite insulators. Finally, the impact of electric field strength, conductivity, and applied voltage on abnormal temperature rise is discussed. The abnormal heating of the sheath-aged insulator is usually a point source. Partial discharge initiated from defects in the core rod is the primary mechanism of abnormal heating in the decay-like insulators, which exist at the high voltage side, the middle section, and the ground side. The heating phenomenon under low humidity is an important characteristic that varies among composite insulator types. Through simulation, the mechanisms and influencing factors of various kinds of abnormal heating were explored and targeted solutions were proposed.