Study on Mechanical Characteristics of Typical Tension Insulator Fitting Strings Under De-Icing Load in UHV Transmission Lines

The occurrence of icing on transmission lines can lead to ice shedding under specific natural conditions or human interference, leading to vertical vibrations in the transmission conductors. In severe cases, this can result in flashover between phases of the earth conductor, damage to line fittings, conductor breakage, and tower collapse accidents. In order to investigate the impact damage experienced by line fittings during conductor de-icing, a finite element model was developed for the conductor-tension insulator string, with a specific focus on typical high-voltage transmission lines. The time history curves of the tension string during dynamic response under de-icing conditions were analyzed. Additionally, a finite element model was developed for typical fitting strings, enabling simulations of their mechanical characteristics. The dynamic response time history curves recorded during the de-icing process were used as the input for simulations. The study revealed that the tension connecting plate experienced maximum stress in areas of shape variations and connecting holes, with stress values ranging from 253.9 MPa to 506.2 MPa in the intermediate section. The stress distribution in the fittings exhibited a consistent pattern, characterized by stress concentration in the circular hole area where loads are applied and in the area where connecting plates undergo a transition from thick to thin in the connecting area. These findings hold some reference significance for enhancing the design of connecting fittings.