Statistical Analysis of Switching Overvoltages and Insulation Coordination for EHV Transmission Line

Summary

The rapid increase in transmission voltages to fulfil higher demand of the transmitted powers yields to put the switching surges as the governing factor in the insulation design process for EHV and UHV systems. The modern methods of insulation coordination make use of probabilistic concepts and statistical procedures especially for very high voltage systems. In this paper, a sophisticated and accurate approach to calculate the switching surge flashover rate (SSFOR) using Adaptive Neuro Fuzzy Interface System (ANFIS) is developed. The variation of switching overvoltages distribution along the transmission line under different system conditions is investigated. The statistical distributions of energization overvoltages for a typical Egyptian 500kV double-line from High–Dam to Samalut are derived from the results of 100 energization cases with statistical (random) 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 various parameters on the energization overvoltages distribution such as line length, source strength and the use of shunt reactors to control the switching surge overvoltages are considered. The developed ANFIS system estimated the SSFOR for different input parameters for both the switching overvoltages and the insulation strength distributions with high accuracy.

Additional informations

Authors

Khademi Mohammad Mehdi, FARINAS Marie Isabelle, Fattahi Fateme, Ferraz Guilherme Martinez Figueiredo