Lightning protection technology based on LPM for ± 1500kV UHVDC overhead transmission lines

With development of the China’s strategy, the Belt and Road, there will be a large number of transnational networking and cross zone networking needs of power grid development in the future. With the rapid development of the society, the area of the transmission corridor will also become an important factor restricting the development of the power grid, and the higher voltage grade UHVDC transmission lines can greatly reduce the line corridor. Based on the above two considerations, it is urgent to carry out the preliminary study of HVDC transmission technology with higher voltage level. Among them, China’s transmission needing higher voltage grade transmission technology is mainly based on reducing the coverage of transmission corridors. When the transmission distance is more than 5000 kilometers, and the required transmission capacity exceeds 20 million KW, the transmission capacity of the current ±1100kV UHVDC project is exceeded. The higher voltage level transmission technology is needed. For example, 4 UHVDC lines in Hami and East China can be replaced by2 higher voltage UHV transmission lines in 2030, which can further save 20%~30% of line corridors. Therefore, it is possible to consider the development of a transmission system with a higher voltage level of ±1500kV. The voltage level rises from ±800kV and ±1100kV to ±1500kV, the height of pole and tower will rise, and the line is more easily struck by lightning. The lightning protection of the line should be paid attention to. In this paper, the calculation method of lightning shielding failure and strike back flashover rates of lightning strike was given. The preliminary estimation of the possible ±1500kV pole tower and line parameters was carried out. Under this boundary condition, the lightning shielding failure and strike back flashover rates were calculated, and the results were evaluated and analyzed. The requirements of grounding resistance and the recommended value of the protection angle for the ground line were given. If the lightning flashover rate of ±1500kV overhead transmission lines was less than 0.1 times / 100km. a), the earth wire protection angles were recommended as follows under different terrain conditions. For plain area transmission lines, the earth wire protection angle can not be greater than −5 degrees. For hilly area transmission lines, the earth wire protection angle cannot be greater than −15 degrees. For mountain area transmission line, the earth wire protection angle cannot be greater than −20 degrees. The higher the voltage level and the greater the transmission flow is, the greater is the loss caused by lightning and other reasons. In order to prevent the occurrence of malignant accidents, it is necessary to carry out the research of lightning early warning technology. Lightning warning technology of transmission lines based on customized numerical weather prediction technology has been highly valued in recent years. This paper analyzed the sensitive meteorological factors of lightning early warning of transmission lines by means of factor method and principal component analysis, and putted forward a scientific and reasonable lightning early warning index to guide the safe production of power grid. The research results in this paper can provide guidance and reference for the development feasibility and safety of the future voltage level of ± 1500kV or even higher.