Lightning Protection Performance of Long Span Section in ±1100kV UHVDC Transmission Line

According to the operation statistics of HVDC transmission lines in China, the blocking accidents caused by lightning strike on single and double poles of HVDC transmission lines occur from time to time. Lightning accidents have always been in the first place of all kinds of faults, and lightning damage has become a huge hidden danger affecting the safe operation of UHVDC transmission equipment. Lightning protection must be paid enough attention to in line construction and operation and maintenance work. For long span high tower of ± 1100kV UHVDC transmission line, due to its high tower height, long span, high lightning probability, and lightning accident is not easy to repair, its lightning protection performance is one of the key issues of transmission line lightning protection. Scientific evaluation of lightning protection characteristics of ± 1100kV UHVDC transmission line in long span section and improving the effectiveness of lightning protection design of transmission line have become the research hotspot and difficulty to be solved. In this paper, the lightning withstand performance of long span section in ± 1100kV UHVDC transmission line is studied, and the calculation method of lightning withstand performance of ± 1100kV long span section is proposed. The shielding failure flashover rate, strike back flashover rate and lightning withstand level of strike back are obtained. Because the span tower adopts the protection angle of -5.9° and the tower head gap is controlled by the working voltage gap, the actual gap of lightning flashover is larger, and the shielding lightning protection performance is better. The mean time between shielding failures of ± 1100kV UHVDC Yangtze River long span is greater than 64 years. The strike back lightning withstand level of each tower is above 260kA. The strike back lightning withstand level of each tower of ± 1100kV Yangtze River span is relatively high, and the average time without fault is long. The mean time between lightning stroke fault of ±1100kV UHVDC Yangtze River long span section is 52 years, equivalent to lightning flashover rate is 0.656 times/(100km•a), which is larger than the index of mean time between lightning stroke fault of 50 years. The tower design of ±1100kV UHVDC Yangtze River long span section meets the requirements of lightning protection.