Estimation of Switching Surge Flashover Rate for a 1200 kV UHVAC Transmission Line by Considering Switching Overvoltage Wave shape

The insulation of the power transmission systems experience stresses due to overvoltages and hence the insulation design of Extra High Voltage and Ultra High Voltage systems depend on the switching overvoltages rather than lightning overvoltages. Insulation failure probability under switching overvoltages is the main impressive concern in the estimation of switching surge flashover rate. . In this paper a new method is used to estimate the switching surge flashover rate of insulation under switching overvoltages generated during line energization, line re- energization, fault initiation and fault clearing of unloaded transmission line, which considered the variable characteristics of the insulation strength of the transmission line according to the switching overvoltage wave shape. The results focus on the comparison between traditional and new methods which considers the effect of the front time on the first 1200 kV UHVAC transmission-line in India.