摘要
绕击是引起超高压、特高压输电线路雷击跳闸的主要原因。将低电压等级输电线路绕击防护经验直接外推至更高电压等级时具有一定的局限性,可能导致新建线路的绕击耐雷性能显著低于预期值。基于先导发展的绕击分析模型细致地考虑了影响雷击发展物理过程各种因素的影响,较传统工程化分析方法更适用于新建电压等级线路的绕击性能评估。但由于对雷击物理过程和长间隙放电机理认识的不足,不同时期不同学者对雷击过程描述所采用的模型和方法不尽相同,若将现有学者所提出的绕击分析模型直接用于工程中,不同分析模型所得结果差异较大。为此,通过对比现有的雷电观测资料,认为Cooray提出的下行先导通道模型与最新的雷电观测结果比较相符;对迎面先导起始工程判据的对比分析结果表明,当导线对地高度<10.0 m时,Rizk感应电压法和临界电晕半径法计算得的先导起始电压结果一致,外推至实际导线对地高度时,Rizk感应电压法的计算结果与长间隙放电理论相违背;同时依据长间隙放电理论,提出了下行先导和迎面先导的相对速度比近似等于迎面先导通道单位长度电压降与导线感应电压增量之比的迎面先导持续发展条件,建立了基于Schwarz-Christoffel变换的能考虑任意地形的2维特高压输电线路雷电屏蔽分析模型;该分析模型解释了传统先导发展模型无法解释的特高压输电线路ZMP2和ZBS2型杆塔的中相屏蔽问题。计算结果表明,在典型的平原、斜坡和山顶地形下,ZMP2和ZBS2型杆塔的绕击跳闸率低于设计预期值0.1次/(100 km.a)。
The shielding failure analysis model by means of the leader progression model takes care of the involved phenomena mainly the propagation of the leaders and the inception and propagation of upward leader from earthed structures, which is more suitable for the lightning shielding performance assessment of UHV transmission line. But the lack of the physics background of the lightning discharge and the long air gap discharge, the leader progression models proposed by different scholars differ from each other. Consequently,the recent lightning observation resuits are analyzed, it is concluded that the downward leader channel model proposed by Cooray is consistent with the lightning observation result. The contrast analysis result of upward leader inception criterion indicates that the Rizk criterion and the critical corona radius conception are equivalent when the gap length is ~10.0 m. The calculation result of Rizk criterion conflicts to the test result of laboratory long air gap discharge when gap length extrapolated to the actual transmission line. A new continuous upward connecting leader model based on the mechnism of long air gap discharge is proposed in this paper, the velocity ratio between the downward leader and the upward connecting leader can be approximately equal to the ratio between voltage drop per unite length of upward leader and the induced voltage increscent of conductor, a new two dimension lightning shielding failure analysis model for UHV transmission line is established which can take into account of the arbitrary terrain by using Schwarz-Christoffel transform. The lightning shielding performance of middle phase is clarified by employing this model. The lightning shielding performance of ZMP2 and ZBS2 on typical plain, slope and mountaintop area are calculated, The calculated results indicate that the lightning shielding failure flashover rate is less than the designed value 0.1 flashes/（ 100 km.a）.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2010年第1期196-204,共9页
High Voltage Engineering
基金
国家自然科学基金(50737003)
国家电网公司十一五科技项目(SGKJ[2007]756)~~
