Lightning Protection for the Transmission Line of ± 800kV UHVDC Single Circuit and 500kV EHVAC Double Circuit Erected on the Same Tower

For some ± 800kV UHVDC projects, due to the limitation of corridor, some transmission lines need ± 800kV UHVDC and 500kV EHV AC circuit to be erected on the same tower. When ± 800kV transmission line and 500kV line are erected on the same tower, the height of the tower is further increased, and the lightning area is increased, so it is important to research the lightning protection and adopt proper lighting protection strengthening measures. In this paper, the lightning protection scheme is determined by the standard named as “Guide for lightning protection of overhead transmission lines”. Based on the transmission line of ± 800kV UHVDC single circuit and 500kV EHVAC double circuit erected on the same tower from Baihetan to Zhejiang, the preliminary results were given. To meet the control value of flashover rate, two lightning protection strengthening measures were proposed, and the results have been used in the design of the transmission line from Baihetan to Zhejiang.