Xiaolan Li

Evaluation of Lightning Flashover Risk of HV Overhead Transmission Lines

Based on the idea of risk evaluation proposed by IEC standard 62305-2, an evaluation method of lightning flashover risk of HV overhead transmission lines is proposed in this paper. The method consists of three important parts: statistics of lightning parameters along the transmission line corridor, computation of lightning flashover performance of each tower as well as the whole line, and definition of lightning flashover risk grade. The method is expounded with an example of lightning shielding failure flashover risk evaluation of a 500 kV transmission line. The evaluation results show that the evaluated risk grades of the line have a good agreement with the operation of the line, and the shielding failure flashover risks of the line have big temporal and spatial differences. The reasons for the worse grade of lightning flashover performance of towers are obtained simultaneously through the method, which would increase the technology-economy rate for the improvement of lightning performance of transmission lines. Evaluation of lightning flashover risk provides a good strategy for power supply companies to master and improve the lightning performance of HV overhead transmission lines.

Study of lightning stroke trip-out fault analysis for transmission line

Based on the research of lightning stroke fault character discrimination method and lightning protection calculation method for transmission lines, the analysis method of transmission line lightning stroke trip-out fault is proposed in this paper. It includes 4 parts: collection and sorting of operation materials, information inquiry of lightning activities, judgment and analysis of lightning stroke accident character, and lightning protection performance calculation. The value of fault analysis is looking for the potential law of lightning faults, through many times of lightning failure analysis. The conclusion will provide specific guidance and advice for lightning protection measure implementation. An example of lightning stroke fault analysis for once lightning trip-out fault of 750kV transmission line in the year of 2009 is given in this paper. According to the line and fault data provided by operating units, compared with the detection information of LLS, the lightning withstanding level of shielding failure and back flashover were calculated. This trip-out fault was caused by lightning shielding failure, and the lightning currents which might cause this fault were found out. Because of the high height and complex topographical feature of tower, the transmission lines in this area were easily to be stroke by shielding failure. And the outside line located on the slope need to be paid much more attention to the shielding failure protection.

Analysis and recurrence of lightning stroke accidents for three gorges 500-kV transmission lines

Lightning stoke has become the first environmental factor which influences the safety of 500-kV power grid in Three Gorges near area. To grasp the operation level of transmission lines, analyze and recur the lightning stroke accidents, and summarize the characters, are the bases of finding and guiding the effective lightning protection measures. In this paper, a method of recurrence for lightning stroke accidents of transmission lines was researched. Over 10 times of 500-kV lightning stroke accidents for about 15 lines in Three Gorges near area during the year of 2007∼2009 were recurred and analyzed. Combined with the lightning detection information and simulated calculation, the range of lightning shielding incidence points were concluded. The conclusions and characteristics of accident recurrence and analysis would provide good references for the lightning protection performance improvement.