Evaluation of lightning - induced temporary faults in transmission lines with respect to grounding system effecttiveness

High Voltage Transmission Lines are subject to numerous faults throughout the year. These faults can be broadly categorized as ice load failures, route-related faults, third-party interferences, mechanical damage to conductors and fittings, and lightning-induced disconnections. Among these, lightning is one of the most significant causes of faults. While previous studies in the literature have primarily focused on parameters such as insulator length, lightning impulse voltages, and general protection systems, comprehensive modeling approaches that consider different grounding configurations and regional soil characteristics in relation to lightning-induced faults remain limited. This thesis proposes a novel approach to analyze the performance of grounding systems under various soil structures and configurations in response to lightning-induced transient disconnections. Rather than examining a single system, multiple scenarios are modeled based on field-measured soil resistivity values, enabling a comparative evaluation of system responses to lightning impulses. In this way, the combined effect of soil structural characteristics and different grounding electrode designs can be thoroughly assessed. Although the numerical modeling tools employed in the study (IPI2WIN and PSCAD) have been previously used separately in different research contexts, their integrated use with real field data in the specific context of lightning-induced transient faults is relatively rare in the literature. Therefore, this thesis provides a novel contribution to the field. The outcomes of this study are expected to directly inform the field planning practices of organizations such as TEİAŞ by contributing to the development of engineering solutions tailored to regional soil conditions and enhancing the lightning protection of transmission lines. Furthermore, the study offers an original academic contribution by re-evaluating grounding infrastructure in transmission systems and identifying optimal grounding designs against lightning strikes. The effects of lightning-induced transient disconnections on grounding systems will be analyzed through both numerical modeling and field measurements.