Vulnerability assessment of the power grid against progressing wildfires

• Wildfires affect the available capacity of transmission lines in their vicinity.
• A model is proposed to calculate dynamic rating of lines exposed to wildfire.
• We modify line rating based on the heat released by a progressing wildfire.
• If line rating is not modified, heat may result in line damage and safety issues.
• Updated line rating leads to suboptimal operating point for the power system.

Wildfires are common in many forest and grassland ecosystems. Power transmission lines are vulnerable to wildfires in their vicinity, mainly due to increased conductor temperatures as a result of heat released by the fire. This may damage the conductor and lead to violation of safety clearances between conductor and ground. To address the situation, a power system operator may dynamically alter the ratings of the lines in the affected areas to reduce the current flowing through them, thereby assisting with conductor cooling. A unified model is proposed here that allows for dynamically changing the thermal ratings of conductors in the vicinity of a wildfire. The proposed model incorporates the radiative and convective heat released due to a progressing wildfire into the conductor thermal rating calculation in order to derive the updated conductor rating. Case studies are presented to show the effects of a progressing wildfire on a power system. It is shown that dynamically changing the ratings of power lines changes the flow of power through the network, moving the system towards a sub-optimal operating point. Under heavy loading conditions, this may even lead to imbalance between load and generation, therefore forcing involuntary load shedding to avoid system collapse.