Real-Time Grid Automation Vs. Power Interruptions

Are you a fan of the underdog achieving improbable success? It’s a story as old as humankind. It taps into our basic nature of hard work, overcoming, and resilience. That’s why what’s taking place on today’s distribution system is so compelling and feels more meaningful. For years industry experts and authorities have said investments in the distribution system are lagging behind those of the transmission system. Of course, the distribution system has always had a lower profile, and the transmission system has always had those big-ticket projects.

It’s easy to see how the underdog concept came about but is it accurate? With extreme weather-related storms and growing power demand, it required a shift to an end-to-end modernization strategy for the entire power delivery system. So underdog may not be accurate, but stereotypes die hard and need a shot of reality to change. A perfect example of this comes from the Edison Electric Institute (EEI). EEI anticipates that its members’ power grid investment will be approximately US$1.4 trillion from 2025 to 2030. Interestingly, the members predict that they have spent about US$207.9 billion when the final 2025 dollars are compiled.

The report also included a graph of how those dollars are broken-down with 32%, or roughly US$66.5 billion going to distribution upgrades. EEI went on to say that member spending on the distribution infrastructure will remain their largest single grid-related capital expenditure for the near future. Don’t forget, those expenditures represent more than wire and poles especially since distribution system has gone digital and one in particular is raising modernization eyebrows with its potential. It’s DA/FLISR (Distribution Automation/Fault Location, Isolation, and Service Restoration)!

Consolidating Technologies

Automated restoration on the distribution system, now commonly referred to as DA/FLISR has reached a level of maturity that’s rapidly driving expansion of deployments at scale. It evolved from recloser loops schemes to the present version of DA/FLISR. DA/FLISR first appeared in the 1990s as utilities looked for ways to dramatically improve distribution system reliability. Since that time there have been several incarnations of DA/FLISR ranging from peer-to-peer approaches to centralized rules-based solutions.

Modern adaptations have reached a new level of sophistication, taking advantage of the integration of DA/FLISR into ADMS (Advanced Distribution Management Systems), which is grabbing the attention of the industry. That advancement is preparing DA/FLISR to be more responsive to dynamic distribution systems with DERs (distributed energy resources), two-way power flow, and future optimized network topologies. DA/FLISR is a key step and fundamental element for decentralization of the grid.

It’s been said that DA/FLISR systems are an efficient approach for addressing the unpredictability of the modern distribution system in an unstable environment. They also significantly improve the operators’ situational awareness, responsiveness, and overall performance while reducing the influence of outside forces on system reliability. At this point, it’s time to talk with an expert about DA/FLISR, so “Charging Ahead” contacted Brian Deaver. Mr. Deaver is a senior technical executive and research manager for distribution operations at EPRI (Electric Power Research Institute), an independent, non-profit energy R&D organization.

Expert's Perspective

Mr. Deaver began saying, “DA/FLISR is a high value solution where the distribution system responds to a fault automatically. It isolates the fault and then through switching it reroutes power from another direction to restore as many customers as possible. When DA/FLISR was first introduced, there was only one source of power for the feeder, which came from the breaker in the substation. The control logic for those solutions could be customized for that normal configuration. Today, however, it’s possible to have distributed energy resources (DER) providing power from within those feeders, which greatly complicates the fault isolation and restoration process. Modern DA/FLISR systems must recognize and respond to challenging system interactions not experienced in earlier distribution networks. They must operate under unusual system conditions, which requires thorough testing and validation prior to deployment.”

Deaver continued, “EPRI's role as an independent, research organization is to foster a standards-based environment, which enables utilities to integrate their diverse technologies into a cohesive, interoperable DA/FLISR system. A typical utility employs a number of distribution automated devices with a variety of abilities from multiple vendors that all have to work within the DA/FLISR’s capabilities. Essentially, it needs interoperability and tech-agnostic platforms to maximize the utility’s value of its existing asset investments.”

Mr. Deaver explained, “In addition to needing a tech-agnostic approach, EPRI is actively involved in developing system models and comprehensive industry standard test cases for DA/FLISR acceptance testing plans. These elements are critical for improving understanding, validation and deployment of fully automated DA/FLISR systems. It’s especially important since there aren’t any standardized performance testing procedures available for DA/FLISR systems. That’s why EPRI is working on developing a framework for utilities and vendors to test and expand their confidence in DA/FLISR systems before full-scale implementation on specific utility infrastructure. It can enhance operator trust and identify performance restrictions without impacting the utility. Standardized performance tests detect potential points of failure and create a level of confidence necessary to achieve the full potential benefits of a DA/FLISR solution, which can be significant.”

Concluding Deaver said, “Additionally, there’s a great deal of research going on to evaluate how the high penetrations of DERs affects DA/FLISR operations because utilities must understand the impacts of these elements on day-to-day operation. Models and techniques to reproduce how DERs behave on the distribution network and reduce their negative impacts are vital. We need to understand the effectiveness of the DA/FLISR system under realistic conditions and events. By taking advantage of these capabilities, distribution system operators can increase their understanding and confidence in DA/FLISR systems on their network, which will pay off with better utilization.”

Implementing DA/FLISR

The global DA market including FLISR was projected to reach US$21.5 billion in 2025 according to DMR (Dimension Market Research). They also expect it to grow to US$70 billion by 2034 for a CAGR (Compound Annual Growth Rate) of 14.0%. The marketplace for DA/FLISR is a growing sector. It’s driven by the need for enhanced grid reliability and the integration of renewable energy sources. The continued expansion of DA/FLISR technologies enables a growing number of utilities to improve their distribution system’s reliability, so let’s look at a few.

A DOE (Department of Energy) sponsored study on the potential for FLISR to improve reliability. One of utilities taking part was Pacific Gas & Electric (PG&E). DOE reported the study results were promising. PG&E deployed FLISR technology on approximately 30% of its circuits, costing US$194 million. The study reported, the implementation “derived an estimated 391 million avoided customer outage minutes, which translates to a benefit of US$828.8 million.” That’s a pretty good rate of return for the funds expended.

National Grid expanded its FLISR coverage in 2025. The end of March 2024 saw about 6.4% of its NY customers on FLISR circuits. That expanded to approximately 9% of its NY customer-base by the end of March 2025, which represents about 152,000 customers on 350 FLISR schemes. National Grid has set a goal of having 60% of it NY customers connected to FLISR circuits in the near future.

DA/FLISR technology has been part of Southern Company’s grid modernization program for over a decade. It has significantly reduced outage impacts across their service territories. One of their subsidiaries, Alabama Power estimated “it has prevented more than a million customers from experiencing sustained outages.”

Boosting Resilience 

DA/FLISR implementations are revolutionizing electric distribution systems. Instead of widespread outages, DA/FLISR limits a fault to a small segment. The duration of the outage is shorten by quickly restoring power to most customers within seconds or minutes, which means a more stable power gird. Automating fault response and rerouting power lowers CAIDI (customer Average Interruption Duration Index), SAIDI (System Average Interruption Duration Index), and SAIFI (System Average Interruption Frequency Index) numbers.

Several studies have shown that CAIDI and SAIDI are significantly reduced by minimizing outage durations. SAIFI improvements are less evident because it can’t prevent factors like tree contact or equipment failure from happening but knowing areas prone to this helps significantly. These are the key reliability metrics used to measure utility performance and compare how well their distribution network is performing against other utilities’ performance. Utilities with high CAIDI, SAIDI, and SAIFI numbers will get more scrutiny from regulators and customers alike. They look at utilities with high numbers in these categories as not being as reliable or resilient.

No matter how you look at it, it puts pressure on utilities to lower those indices by adopting cutting-edge DA/FLISR technologies. DOE estimates that DA/FLISR can reduce outage times by up to 50%. They also estimate that over 60% of US utilities had deployed some form of ADMS by the end of 2025, so it’s a trend that’s gaining momentum. Still there are those who are uncomfortable. It’s too trendy, but there’s a lot of experience with DA/FLISR. And it’s needed now!