The increasing threat of extreme weather and catastrophic wildfires is driving TEP to make operational adjustments for additional safety.
TEP works year-round to replace poles, upgrade equipment and make other improvements that help our local energy grid withstand increasing heat and fierce summer storms. We also focus on vegetation management, monitored by ground and helicopter patrols for our higher voltage lines. To reduce both outage and wildfire risks, we inspect our lines, trim away any nearby vegetation and issues work orders when repairs or upgrades are needed.
These and other efforts are documented in a new wildfire prevention plan that we developed over the past year and implemented on April 1. The plan is based on a thorough assessment of our entire energy grid that identified the areas that face the greatest risk of a utility-caused wildfire. The plan outlines the steps TEP will take to prevent such fires, particularly during periods when wildfire risks are high.
Here’s a glimpse into how we did it and the new technology and approaches we’re using to reduce wildfire risks.
Wildfire modeling algorithm
The risk modeling software we used to evaluate the potential for a utility-caused wildfire in the many different areas we serve was highly sophisticated, relying on factors that include advanced weather forecasting, fire behavior modeling and real-time system monitoring.
The best way to forecast the risk of utility-caused wildfires would be to review previous incidents and consider how different environmental conditions might make such incidents more or less likely to occur. Because TEP had so few incidents to work with, we studied power outages, since equipment damage, downed lines and other problems that interrupt service could potentially spark a fire under certain conditions.
To determine how weather might have impacted reliability, we reviewed about 19,500 power outages over the past decade and matched them with historic weather data from the National Oceanic and Atmospheric Administration. While temperature was a factor, the outage rate increased dramatically with wind gusts. For example, our outage rate was 5,000 times higher at wind speeds approaching 60 miles per hour.
We also used computer modeling to simulate the spread of 100 million virtual fires that started under TEP lines. The analysis considered conditions that included historic fire events, vegetation moisture content, topography, building footprints and wind gusts. The model then determined how fast and how far the fire would spread as well as how many structures would be at risk, the acres of territory burned, and the size of the fire, to approximate suppression costs. The model also considered cell phone coverage, sensitive habitats and suppression difficulty based on the terrain.
This modeling informed a risk assessment for TEP’s entire service territory that has identified three risk tiers – areas where customers face moderate, elevated and higher risks associated with utility-caused wildfires. As expected, the higher-risk tiers include some of the most remote areas we serve, with less development and more dry vegetation.
TEP has conducted public outreach in these areas to educate residents about the steps we are taking to prevent utility-caused wildfires. These steps include upgrades and operational changes that will provide greater protections for public safety.
Non-Expulsion Fuses
We’re analyzing the merits of replacing traditional fuses with “non-expulsion” alternatives that eliminate sparks if the fuses trip. Their self-contained design eliminates showers of molten particles and hot metal that could come in contact with vegetation, reducing the risk of fire from electrical equipment.
Our first non-expulsion fuses will be installed later this year on a trial basis. We’ll monitor the performance of this new technology to see if expanded use is warranted, particularly in areas that are more risk-prone to wildfire.
Reclosers
Reclosers aren’t a new technology, but we’re looking more closely at how we use them. They play a critical role in providing safe, reliable power by automatically interrupting and restoring power in response to momentary faults, or interruptions in electric current that cause power outages.
When it detects a fault, the device immediately shuts off the power to the affected section of a line to prevent damage to our equipment or reduce the risk of a fire. It will automatically try to restore power three times – immediately, and then again at 15 seconds and after 90 seconds.
If the fault is temporary, power resumes. Sometimes, that’s the little flicker you see when the power momentarily goes out. If power doesn’t resume, a crew will come out to inspect the segment and make repairs.
The technology:
- improves grid reliability
- reduces the length of outages and how many people are impacted
- improves efficiency by eliminating the need to dispatch crews for temporary issues
However, in risk-prone areas for wildfire, we might temporarily disable recloser operations during periods when wildfire risks are high, eliminating the automatic restoration of power to a faulty line. That will reduce the risk that our electrified equipment might spark a wildfire, such as in the case of a downed line falling into dry brush below. Restoring service will instead be done manually, and only after our field crews have physically inspected the lines and performed any necessary repairs. This practice likely will result in longer outage times, but is an important element of reducing the risk of wildfire and may help us avoid proactively shutting off power to risk-prone areas.
AI cameras:
Cameras that leverage artificial intelligence to help spot wildfires sooner will be installed late this summer along the high-voltage transmission line that delivers electricity from TEP’s Springerville Generating Station through the Gila National Forest.
Six AI-supported smoke detection cameras will be installed along the route on tall communication towers, providing a 30-mile, 360-degree view around the clock. The cameras can detect smoke, distinguishing it from dust or fog, and often within minutes.
Earlier visibility supports a faster emergency response and fire suppression, if necessary. Data collected by these cameras will be shared with state and local agencies to help detect and respond to potential wildfires.
Public Safety Power Shutoffs (PSPS)
As a measure of last resort, TEP stands ready to temporarily de-energize lines in limited, risk-prone areas where a problem with our electrical facilities could cause ignition if certain weather conditions are met.
About 1,300 of TEP’s 455,000 customers live in areas where such PSPS events could occur in response to certain forecasted weather conditions. Our risk modeling software platform does not rely on explicit thresholds for wind speed, humidity or temperature. Those metrics are instead combined with vegetation and terrain factors as well as information about our local electrical facilities to calculate a projected fire risk.
