Statistical Analysis of Switching Overvoltages and Insulation Coordination For a 500 kV Transmission Line

The modern methods of insulation coordination make use of probabilistic concepts and statistical procedures especially for very high voltage systems. This paper presents, a proper approach to calculate the switching surge flashover rate (SSFOR) using Adaptive Neuro Fuzzy Interface System (ANFIS). The switching overvoltages distribution along the power transmission line under different conditions are investigated. The statistical distributions of energization overvoltages for a typical Egyptian 500 kV double-line from High-Dam to Samalut are derived based on the results of 100 energization scenarios by randomly switching using alternate transient program (ATP). The statistical distributions and its key values, such as mean value, standard deviation and 2% statistical overvoltages values have been recorded. The effects of the line length, source strength and shunt reactors for controlling the switching surge overvoltages are demonstrated. The developed ANFIS system is used to estimate the SSFOR for different input parameters for both of the switching overvoltages and the insulation strength distributions with high and comparable accuracy.