As a common disaster on transmission lines， ice disaster affects the safe operation of the power system seriously. A digital twin system for ice shedding of overhead transmission lines was designed and implemented to meet the precise mapping and real-time communication and visualization presentation requirements of de-icing vibrations of actual transmission lines. Firstly， the idea of real-time mapping of physical information was introduced， and the overall framework of the transmission line de-icing digital twin system was built based on the Unity3D platform. Then， an analytical solution based iterative model during any time period was established and solved， and the iterative model was combined with the measured time-varying parameters for segmented iterative correction， so as to complete modeling of the digital twin model. At the same time， the calculated twin data were displayed on the twin interaction platform for transmission line de-icing vibrations. Finally， this system was applied to simulate successive three levels of conductor ice shedding to verify the effectiveness of the model. Experimental results show that the results calculated by the twin model are highly consistent with the actual measurements， and the Mean Absolute Percentage Error （MAPE） of the twin model system is within 0.5%. It can be seen that the proposed method can establish an accurate model that reflects the operating status of the transmission lines.

With the expansion of overhead transmission lines， there has been an increasing number of high-capacity， extra-high voltage， and long-distance transmission line sections， making crossover transmission lines a more common occurrence. The electrical safety gap of crossover lines has become a critical factor affecting the safety of power grid lines. Therefore， a general expression for the spatial configuration of overhead conductors in three-dimensional space was constructed on the basis of a catenary model， and the critical segment method was employed to calculate the minimum electrical gap value within the lines. Then， by integrating the Unity3D engine with the minimum gap calculation program， virtual simulation was conducted， the layout effects of crossover sections under different parameter settings and the locations of flashover faults in the lines were demonstrated by using tower and conductor models in three-dimensional space， and based on the virtual simulation of electrical gap， the minimum gaps under different line parameters were solved. Simulation results indicate that the line crossover angle and the line icing have significant influence on the minimum gap of the lines， validating the effectiveness of the critical segment method and virtual experiments.