Research on the Improvement Measure of Armor Rods Segment of Overhead Ground Wire Based on Multi-Field Coupling

When the power-frequency short-circuit current flows through the armor rods segment on an overhead ground wire (OGW), the OGW at the segment may experience fracture failure due to high temperatures. Consequently, it is necessary to optimize the structural configuration of the armor rods segment. Based on the structural characteristics of the conventional armor rods segment, this paper proposes a stepped-type armor rods segment structure. First, an electromagnetic–thermal coupling simulation model for both types of armor rods segment is constructed, in which the conductor length is determined by the boundary conditions of both the electromagnetic field and the thermal field. The current density distribution and transient temperature distribution under power-frequency short-circuit current are analyzed using the simulation model. Subsequently, based on the simulation results, an evaluation method for the mechanical performance of the OGW considering non-uniform temperature distribution is proposed. This method is employed to compare the high-temperature mechanical properties of the OGW at the two types of ends. Finally, a transient temperature rise experiment is designed to validate the accuracy of the simulation model. The research results show that the simulation model has sufficient accuracy, with an error of no more than 6%. Compared with the conventional armor rods segment, the stepped-type structure effectively avoids the concentration of high-temperature zones. Under identical conditions, the mechanical load-bearing capacity of the OGW at the stepped-type end is higher than that at the conventional end, which can help prevent high-temperature fracture of the OGW to a certain extent.