Evaluation of Corona Loss in 750 kV Four-Circuit Transmission Lines on the Same Tower Considering Complex Meteorological Conditions.

As an important index for measuring the operational economy of EHV AC transmission lines, corona loss (CL) is one of important factors worth considering during the operation and design of transmission lines. The 750-kV transmission lines are mainly distributed in high-altitude areas in northwestern China, where sand storm occurs frequently in spring and autumn. At present, a few researches are available on the evaluation of CL in multi-circuit transmission lines on the same tower in sandy and dusty area at high altitudes. Based on a transmission project with four-circuit transmission lines on the same tower in the north of Xi'an, Shaanxi Province, China, the electric field distributions of bundle conductors under two types of arrangement structure, including six and four cross-arms tower, were investigated. Then, by using the CL equivalent theory, the CL under meteorological conditions of fair, rainy, snowy, foggy, and dusty weather were evaluated. Finally, the optimal phase-sequence arrangement under the optimal tower modes was proposed, and the CL and resistance loss under the selected arrangements were compared.