With forecasts that Climate Change will increase the number of days of extreme fire danger, as well as the duration and intensity of such days, the imperative for mitigating the risk of fires starting from powerlines, and understanding the impacts that wildfires have on distribution and transmission lines has never been greater. In addition, the significant risk to life and infrastructure is compounded by the potential costs imposed on utilities to rebuild damaged networks and provide compensation where liability can be proven. Recent bushfire events in Australia have dramatically illustrated this challenge.
In this context, Working Group (WG) C2.24, has produced Technical Brochure (TB) 868, “Mitigating the risk of fire starts and the consequences of fires near overhead lines for System Operations”. The Australian Convenor of this work was Frank Crisci.
The purpose of this study was to investigate the system operating practices of utilities which operate their networks in elevated wildfire danger environments. In this environment, distribution utilities need to manage the risk of starting a wildfire, while transmission utilities need to manage the risk of a wildfire engulfing their lines and affecting grid stability and security.
A survey was developed to collect the requisite information and identify and collate best-practice strategies into the Prevent, Prepare, Respond, Recover (PPRR) framework of Emergency Management. From the survey results, distribution utilities are the ones most concerned with wildfire risk management and consequently most of the study was focused on them. The distribution utilities that are most advanced in wildfire risk mitigation have implemented multiple strategies for fire start risk mitigation, including:
To better understand their risks, utilities undertake wildfire risk modelling to calculate potential consequences from fires started from their powerlines, under a range of weather patterns and fuel volumes and fuel curing. This then informs them of the potential consequences or threats from such fires.
The study has shown that one key driver for the urgency and intensity with which utilities address wildfire risk mitigation, is whether or not the utility has experienced fire starts from its lines, which is also a key factor in the extent of the regulatory regime imposed on utilities. As a result, wildfire risk mitigation is a strong operational focus for distribution utilities, particularly in Australia and the USA. This focus extends to collaboration with research institutions and technology vendors to advance the science of wildfire risk reduction, as well as coordination of fire risk mitigation with governmental fire-fighting agencies.
The increasing stringency of regulatory environments, coupled with the difficulties of obtaining adequate insurance cover and the potential increased severity and frequency of elevated fire danger weather from climate change, presents utilities with major challenges in their efforts to mitigate wildfire start risk. Increasing risks and liabilities are driving utilities to consider the greater use of shutting down power. This can have significant consequences for the served communities, particularly during heatwaves. An approved framework for taking this action is important to ensure this is only used when absolutely necessary.
The PPRR framework developed from this study can serve to give utilities a checklist against which to
compare and optimise their existing network operations and mitigate the risk of fires.