Research on the lightning shielding failure characteristics of UHVDC transmission lines is important for adequate transmission line protection and safe operation of a power grid. Focusing the competition characteristics of upward leaders in the lightning attachment process, this work provides technical reference for efficient evaluations of lightning shielding failures and reliable lightning protection designs of UHVDC transmission lines. The charge simulation method is employed to calculate electric field distributions. Based on the calculation and some data obtained by recent long-gap discharge and lightning observations, the effect of several upward leaders starting from UHVDC transmission lines on lightning attachment processes is studied by numerical simulation. The results show that the upward leader inception is delayed, the propagation velocity is smaller, and the propagation direction of the upward leader is changed with interaction among all upward leaders, which influences the selection of lightning striking point. Therefore, in order to improve the accuracy of calculating the lightning shielding failure rate of UHVDC transmission lines, the interaction characteristics of upward leaders should be taken into account . In addition, an analysis of the influence of operating voltage and the protection angle of UHVDC transmission lines based on competition mechanism of upward leaders is made. It is found that the existence of operating voltage mainly affects the ability of the conductor and the overhead ground wire at the same side to incept upward leaders, while the protection angle mainly affects the position of the "starting points" of upward leaders. The results indicate that positive polar conductors should be installed closer to hillsides and the negative protection angle of towers is suggested.
高压直流输电线路 竞争机制 人发 闪电 雷电绕击 防雷保护设计 连接过程 雷电屏蔽