The insulation of the power transmission system experiences stresses due to power–frequency voltage under normal operating conditions, temporary overvoltages at or near power–frequency and transient overvoltages arising either from switching operations and faults or from lightning discharges. However, in the insulation design of extra-high-voltage and ultra-high-voltage systems, transient overvoltages arising from switching operations and faults become the controlling factor. Insulation failure probability under switching overvoltages is the main impressive concern in the estimation of switching surge flashover rate. In this paper, a practical method is used to estimate the switching surge flashover rate of insulation under switching overvoltages generated during energization, re-energization, fault initiation and fault clearing of an unloaded transmission line, which considers the variable characteristics of the insulation strength of the transmission line according to the switching overvoltage waveshape. The results focus on the comparison between traditional and practical methods which considers the effect of the front time on the first 1200-kV UHVAC transmission line in India.

中文翻译：

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考虑切换过电压波形的1200kV特高压交流输电线路切换浪涌闪络率估算

输电系统的绝缘会因正常运行条件下的工频电压、工频或接近工频的临时过电压以及开关操作和故障或雷击放电引起的瞬态过电压而承受应力。然而，在特高压和特高压系统的绝缘设计中，开关操作和故障引起的瞬态过电压成为控制因素。开关过电压下的绝缘失效概率是估计开关浪涌闪络率的主要问题。本文采用一种实用的方法来估算在通电、再通电、再通电过程中产生的开关过电压下绝缘的开关浪涌闪络率。空载输电线路的故障引发和故障清除，根据投切过电压波形考虑输电线路绝缘强度的可变特性。结果集中在考虑前沿时间对印度第一条 1200 kV UHVAC 输电线路影响的传统方法和实际方法之间的比较。