Analysis of the Stranding Effect on the Surface Voltage Gradient of Transmission Line Conductors with Round Strands

For high-voltage power transmission, the surface voltage gradient (SVG) of the conductor plays a crucial role in meeting corona performance requirements. The SVG is greatly impacted by the smoothness of the conductor’s surface. Under identical conditions, the SVG of smooth, round conductors differs from that of stranded conductors with the same outer radius. This paper uses Finite Element Analysis (FEA) to study the effect of different stranded conductor geometries and three-phase line topologies with stranded conductor bundles on the SVG. Although industry standards and the scientific literature often rely on simplified smooth-cylinder approximations, this research demonstrates that surface irregularities significantly increase electrical stress compared to idealized smooth surfaces. Through simulating various three-phase configurations, the study reveals a nearly constant field enhancement factor across diverse stranded designs. These results enable us to apply formulas developed for smooth conductors to more realistic power line applications involving stranded conductor bundles. Consequently, this FEA approach offers engineers a precise, versatile method for designing high-voltage transmission lines. The findings presented here facilitate a deeper understanding of the SVG surrounding stranded conductors, particularly with regard to its influence on corona phenomena.