Analysis, simulation and experimental research on the mechanisms of lantern-shaped strand defects in the conductor construction of transmission line

This paper focuses on theoretical, numerical simulation, and experimental research on the lantern-shaped strand defect that arises in tension stringing constructions of large-section conductors. Starting from considerations for factors such as the construction environment and the characteristics of the conductor passing through blocks, this paper presents the causes of conductor torque generation and analyzes the distribution of axial forces on the outmost layer strands and the outmost adjacent layer strands of the conductor when subjected to bending and twisting. Taking into account the contact forces between strands in different layers, this paper thoroughly examines the mechanical causes that lead to the occurrence of the lantern-shaped strand defect in conductors. It concludes that the axial compression and the external contact force acting on the outermost adjacent layer strands are crucial in the formation of the lantern-shaped strand defect. To numerically simulate the lantern-shaped defect, a finite element model is developed to replicate the passage of a 1250 mm2 large-section conductor through the block system. Furthermore, considering actual working conditions, a test equipment is designed and constructed to replicate the lantern-shaped defect. The shape and size of the lantern-shaped defect obtained from the tests exhibited a substantial agreement with the simulation results, suggesting concordance between theoretical analysis and real situation. This research methodology can be used to analyze defects in conductors with varying sections, serving as a theoretical foundation for the prevention and control of construction defects in conductors.