Resilience of Substations to External Hazards

This paper presents design guidance and recommendations aimed at enhancing substation safety and resilience by recommending minimum clearance distances and mitigation measures against these risks.

Wildfire risk and mitigation: Substations in rural and remote areas, especially in northern

Scotland, face wildfire threats due to surrounding vegetation and seasonal conditions. A wildfire risk assessment is essential, and creating defensible space zones around substations can prevent fire spread. Additional measures include maintaining clear access routes for firefighting vehicles. Regular inspections ensure compliance with these zones.

Design lifecycle integration: Fire prevention and mitigation measures should be integrated throughout the substation lifecycle, including planning, design, operation, and maintenance, to effectively reduce risks from external hazards.

Proximity to wind turbines: Substations must be sited at safe distances from wind turbines to mitigate risks from turbine toppling, wake effect, ice throw, and ice fall. The recommended minimum distance between a substation boundary and the nearest wind turbine shall be 1.5 times the sum of the turbine’s hub height and rotor diameter. Battery energy storage system (BESS) fire risks: For grid-scale lithium-ion BESS installations, a minimum separation of 30 metres from substation equipment and buildings is advised to reduce fire risk and ensure safe firefighter access. This distance can be adjusted if fire barriers or other mitigation measures are implemented.

The recommendations in this paper aim to support substation design by enhancing safety and resilience against such risks. The engineering guidance presented outlines a set of general "best practice" principles for locating substations near wind turbines or BESS sites, or in areas prone to wildfires. These recommendations represent minimum requirements and may be adjusted based on project-specific studies and detailed risk assessments.