Wildfire awareness and response plans are critical for electric utilities that want to significantly reduce or even eliminate the risk of wildfires igniting from power lines in their service areas. Within these plans, the environmental conditions that will trigger electric utilities to take actions to prevent the ignition and spread of wildfires should be identified.
These environmental “triggers” should be well documented by the Wildfire Awareness Manager and their team ahead of wildfire season. The triggers will initiate changes in standard operating procedures, particularly protective relay and automatic reclosing practices, to emphasize wildfire prevention.
During wildfire season, the Wildfire Awareness Manager and their team will monitor environmental events and implement enhanced procedures when the risk moves from low to medium, high, or extreme. A plan will be in place in advance of the season. Let's explore potential environmental triggers and monitoring practices.
Environmental Triggers That Increase Wildfire Risk
Environmental conditions can affect dry material ignition and wildfire spread. Increased ambient temperature, low humidity, days without rain, and solar radiation are environmental triggers that increase the risk that a faulted electric transmission or distribution line will ignite a wildfire. Dry lightning may be a trigger because it can strike transmission and distribution line structures and poles, creating flashovers and resulting in arcs that radiate energy to nearby burnable material.
High winds are another important environmental event that can blow trees, tree limbs, and other peripheral objects into overhead, open air transmission and distribution lines. These objects create faults that radiate energy to nearby burnable material. High winds can dislodge conductors, snap poles, and break crossarms. Once a wildfire is ignited, high winds increase the rate of wildfire spread.
The Wildfire Awareness Manager and their team must document the location of potentially hazardous areas where environmental triggers may lead to wildfires before wildfire season. This will help ensure that the electric utility is prepared to respond when an environmental event is predicted or occurs.
Update Maps to Include Wildfire Hazard Areas
To create informative and realistic procedures, the Wildfire Awareness Manager must ensure that their utility’s maps and drawings are updated to include wildfire hazard areas. Most electric utilities have thousands of miles of transmission lines that are shown on plan and profile drawings, and thousands of miles of distribution lines that are shown on primary operating maps.
Layers can be added to these digital maps to display the location of burnable organic material zones, such as known areas of dry grass, leaves, hay, duff, peat, etc. Reclosers, with wireless communication to control centers, should be noted when they are placed near burnable organic material boundaries where distribution lines are routed from low-risk areas through high-risk areas.
Peripheral clearance zones should be added as a layer on all maps and drawings that show transmission line and distribution line routes. Peripheral clearance zones are areas where trees are tall enough to contact transmission lines and distribution lines if they fall towards the line. Peripheral clearance zones may contain tall, healthy trees that can be toppled by high wind gusts, such as the tree in Figure 1.
Figure 1 shows a tall, healthy trees that could be toppled by high wind gusts in the peripheral zone along a transmission line.
Near transmission lines, peripheral clearance zones can be minimized by topping tall trees near the right of way and removing trees that are up slope in mountainous areas. Near distribution lines, minimizing peripheral clearance zones may be challenging because homeowners might not want electric utilities to trim trees that beautify their properties.
Monitor Triggers to Decrease Risk
Throughout wildfire season, the Wildfire Awareness Manager and their team must monitor for environmental events, especially those that are occurring near wildfire hazard areas. In the Pacific Northwest, wildfire season is usually late May through September. Starting in May, the Wildfire Awareness Manager must be aware of the daily weather and weekly forecast.
As environmental conditions like weather can change rapidly, a member of the team must be tuned into updated weather forecasts throughout the day. Team members would take shifts to be on call during evenings and weekends, ensuring environmental conditions are always monitored during wildfire season.
Change Procedures as Wildfire Risk Increases
The Wildfire Awareness Manager must have procedures prepared before wildfire season so that the plan of action is known before high-risk wildfire conditions occur. These procedures will outline actions that must be implemented when environmental conditions increase from low wildfire risk to medium, high or extreme wildfire risk.
For example, when winds are forecast to exceed Beaufort Scale 8 (46 miles per hour), electric utilities must operate their systems in the high-risk mode. When winds are forecast to exceed Beaufort Scale 9 (54 miles per hour), electric utilities must initiate power safety shutoffs in wildfire hazard areas. When winds are forecast to exceed Beaufort Scale 10 (63 miles per hour), electric utilities must initiate power safety shutoffs in wildfire hazard areas and nearby areas.
Document, Monitor, Enhance Procedures
By documenting environmental triggers before wildfire season, updating maps to include wildfire hazard areas, and closely monitoring events when wildfire season is occurring, electric utilities can nearly eliminate the risk of their power lines igniting wildfires. Specific procedures for enhanced operations will be discussed in more detail in a future post and are summarized in our whitepaper 10 Best Practices to Reduce the Risk of Power Line Wildfires.
Want to learn more about how Prescient can help your company reduce the risk of wildfires ignited by faulted power lines? Contact us to schedule a free consultation today.
This article was written in collaboration with Prescient's Lead Editor Alyssa Sleva-Horine.
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