Shielding Angle Effectiveness Analysis on 220 kV and 500 kV Transmission Lines Against Lightning Strikes, Including Hillside Considerations

This study analyzes the effectiveness of shielding angle in 220 kV and 500 kV transmission lines as a protection system against direct lightning strikes on phase conductors. Specifically, it focuses on the impact of decreasing the shielding angle (to negative angles) on the line outage rate compared to the backflashover rate. To this end, two transmission line sections of each voltage level are taken as case studies. The electro geometric model is used, and lightning strike simulations are performed using ATPDraw software, considering flat terrain and hillsides up to 30° slopes. Finally, recommendations and strategies to improve the reliability of transmission systems are presented.