Fire is as old as time, and while we have conquered it in countless ways, it still has a habit of showing up unannounced and unwanted. Nowhere is this more evident than in areas of the Western United States, which see numerous wildfires every year that claim lives and millions of dollars in property. Unfortunately, fires that can be caused by and/or destroy utility infrastructure occur in other parts of the U.S. as well. So, are there tools and practices available to help utilities protect their equipment from wildfires and to help minimize the occurrence of power equipment caused fires?
The answer is definitely yes. In states with hot, dry periods where long expanses of transmission and distribution lines may cross high-fuel environments containing dry grass, brush and forested areas, utilities are increasingly turning to granular herbicides to create vegetation-free zones that act as a fire-break to protect their equipment. According to Paul Escobar with SSI Maxim Company, a reduced vegetation zone creates a defensible space where heat and flame exposure to equipment is reduced. Moreover, granular herbicides can be applied around structures with a broadcast spreader and they protect an area for months. Creating a reduced vegetation zone in the vicinity of distribution equipment like pole mounted transformers or capacitors also helps minimize the creation of a fire should an errant spark occur.
In recent years, utilities across the country have been taking steps to increase reliability and resiliency after a series of major storm events caused major outages. For example, CenterPoint Energy developed a hazard tree inspection program after Hurricane Ike in 2008 to periodically inspect important circuits thought to be potentially at risk due to the presence of certain danger trees including palm and pine species. Unitel implemented a vegetation storm resiliency program (SRP) after experiencing a series of extreme weather events and realizing that standard vegetation management practices may provide insufficient protection from extreme events. The SRP goes beyond the company’s traditional core vegetation management program consisting of cyclical pruning and hazard tree removal by conducting detailed tree risk assessment on critical circuits to remove all failure risks and ensure ground-to-sky clearance. Not surprisingly, the storm hardening practices conducted by both utilities also serve to help minimize the risk of fires resulting from vegetation caused equipment damage.
According to Scott Holmquist with Pursue It Consulting, utility companies are increasingly focusing on developing effective wildfire mitigation, vegetation management and pre-treatment programs to minimize losses. Scott’s experience has been that fire retardants in the Long-Term Fire Retardant (LTR) classification have proven to be highly effective for a variety of situations. They can be applied on and around flammable materials to reduce fire intensity, rate of spread and increases safety for those working on a fire line. In addition, LTRs can be applied several days prior to fire passage and remain effective for days and even weeks after application. Wooden poles treated with fire retardants experience greatly minimized damage compared to untreated equipment.
Some observers might argue that the billions of dollars utilities are pouring into smart grid technologies will put an end to electrical equipment related fires. After all, automation technologies can aid in fault location, isolation and restoration and there is no question that system resilience to extreme weather events is improved when equipment has the ability to detect and automatically limit the extent of major outages. However, utilities and researchers are learning that even smart grid enhanced systems are fallible and can be improved upon.
Pedernales Electric Cooperative and other Texas utilities are working with Texas A&M Engineering to address potential sensitivity gaps in some smart grid systems that should further reduce wildfire risks. The team is demonstrating a technology known as distribution fault anticipation (DFA) that was developed at Texas A&M University’s College of Engineering. The technology helps utilities detect multiple line issues that could lead to wildfires by utilizing sensitivity triggered, high fidelity waveform recorders positioned at substations on distribution circuits. An extensive database of collected waveform data has helped researchers identify the characteristics of various line events and develop algorithms to recognize and report them. As an example, the DFA system can help identify and isolate a recurrent fault that left uncorrected might lead to permanent damage and, potentially, a fire.
Ever-improving vegetation management practices, fire prevention/mitigation treatments and advanced technologies are contributing to improved electrical system reliability, resiliency and reductions in fire ignition risk. However, we can never drop our guard because nature, careless humans and malfunctioning equipment keep the risk of wildfires alive. Every additional measure we can implement that improves situational awareness and preparation further reduces the chances that a fire will lead to major losses.