Insulation Performance of a High-Voltage Compact Overhead Transmission Line subject to Tropical Savanna Wildfires

This work aims to investigate the impacts of wildfires on the insulation performance of a high-voltage (500kV) compact overhead transmission line (OHTL) located in the Brazilian tropical savanna. On March $23^{rd}$ of 2013, an intense wildfire under two 500 kV OHTL resulted in three hours of power interruption and loss of 10.9 MW in the Brazilian Interconnected system due to fire-induced flashovers. This event raised questions regarding the effectiveness of the design approach in determining the minimum vegetation clearance distance (MVCD) since the preventive vegetation management, performed following standards and environmental protocols days before the fire event, was insufficient to avoid the outage. This research presents evidence from twenty years of wildfires and 108 outage events resulting from fire-induced flashovers between the years 2013 to 2019, suggesting that the current design approach to determining the minimum vegetation clearance distance may be insufficient to provide reliable electrical insulation in the event of a wildfire. This paper assesses the clearance distances of several line spans subjected to fire-induced flashovers from the perspective of four MVCD calculation approaches and compares the performance, which shows that these methods are insufficient.