Reliability Evaluation of 150 kV Transmission Line in Southern Sumatera Region using Recorded Lightning Data

Reliability of high voltage transmission line against lightning exposure is important consideration for power system network in area with high lightning activity such as Indonesia. Lightning performance evaluation toward existing 150 kV transmission line in Southern Sumatera Region using recorded lightning data is presented in this paper. The existing tower design data is used to create transmission tower model according to Multistory method and the recorded lightning data is used to obtain lightning characteristic for the simulation. Electromagnetic transient program simulation using tower model and lightning data is performed to calculate the overvoltage on the insulator string during direct lightning strike to the conductor and to the transmission tower overhead ground wire. According to the simulation result for shielding failure, it is found that existing tower design using two overhead ground wire gives relatively effective shielding (unprotected area 0.36 meter) with calculated probability of transmission line outage rate due to shielding failure equal to 0.001169 fault/100km/year. The usage of 12 ball and cap insulators for each insulator string gave the transmission tower capability to withstand flashover from 87.19% lightning strike toward overhead ground wire with calculated probability of transmission line outage rate due back flashover equal to 3.0742 fault/100km/years. Total calculated probability of outage rate for existing 150 kV transmission line in Southern Sumatera region equal to 3.0753 fault/100km/years.