Analysis of Lightning-Induced Electromagnetic Pulses on High Voltage Transmission Lines

in this study investigates grounding enhancement techniques for power transmission lines, drawing an analogy with electromagnetic shielding methods. If we look at the basic analogy between electromagnetic shielding and grounding, the purpose of shielding is to prevent electromagnetic fields (both electrical and magnetic) from reaching an area or to reduce electromagnetic propagation. Grounding helps maintain signal quality, eliminate static buildup, and ensure the system meets EMC (electromagnetic compatibility) requirements by safely conducting the shield's parasitic potential to the ground. Examples of such structures include single-point grounding or two-point grounding and the use of mesh. The fundamental principle here is to reduce or prevent the interference of parasitic signals into the protected system. The objective is to improve the reliability and efficiency of transmission systems by optimizing grounding performance. Lightning and electromagnetic pulse (LEMP) intensity and current amplitude data obtained from the Turkish State Meteorological Service (TSMS) were used in the analysis. The electrical performance of the line and its resistance to LEMP-induced faults were evaluated through simulations using the Alternative Transients Program - Electromagnetic Transients Program (ATP-EMTP). The Seydişehir-Akseki-Varsak transmission line was selected as a case study. Results show that grounding improvements led to a significant reduction in the number of LEMP-related outages. Guy wires (GWs) enhanced the electromagnetic coupling between phase conductors and improved the dissipation of LEMP currents into the ground, thereby reducing the equivalent ground resistance. Due to the high cost of line surge arresters, the use of low-cost and easily deployable alternatives such as GWs is recommended. Further analysis on 400 kV transmission lines revealed that GW implementation reduced the flashover voltage at insulator terminals by up to 49%. These findings highlight the importance of cost-effective grounding methods in establishing reliable and sustainable power transmission infrastructure.