Feasibility research of lightning rods installed on the frames of main transformers in 1000KV UHV substation

Because 1000kV UHV substations cover enormous area, it is hoped that lightning rods be installed on the frames of main transformers to reduce installation of excessive independent lighting rods, and thus to reduce substation area and cost. Referring to years of operating experience of many 110500kV substations, lightning rods might be installed on the frames of main transformers to shield direct lightning strokes for 1000kV UHV substations. But for 1000kV UHV substations with high soil resistivity, it is necessary to research on whether lightning rods could be installed on the frames of main transformers.If lightning rods installed on the frame of main transformers of UHV substations as direct lightning protection devices, the lightning rods should be connected to the grounding grid, and install centralized grounding device nearby. When lightning strokes occurring, there will be uneven voltage distribution between the various parts of the grounding device, and there will be backflashover overvoltage between the grounding device and the equipments installed on the grounding device. So for 1000kV UHV substations, whether lightning rods could be installed on the frames of main transformers, the computation of ground potential rise and backflashover should be carried out. The researches mentioned above relied on Fuzhou 1000kV UHV substation. Supposed lightning rods be installed on the frames of main transformers, when the soil resistivity were 50, 400, 1000 and 4200Ω·m, and the lightning current was 250kA, the ground potential rise and the backflashover overvoltages were computed. Results have been already used in the design of Fuzhou 1000kV UHV substation.