Alabama Power is a subsidiary of Southern Company and the largest electric utility within Alabama, delivering power through 85,586 miles of lines in the southern two-thirds of the state. We operate in one of the most storm-prone areas of the country, facing tornadoes, thunderstorms, and tropical storms year-round. The continual rush of disruptive weather events is a looming threat and impacts power reliability and resilience for our 1.5 million customers.
We recognized the importance of minimizing outages on our lateral lines to enhance power delivery to customers. Upon investigating areas of our system with performance concerns, we determined certain fuse-protected laterals, while operating as intended, exhibited a higher degree of unreliability. These traditional lateral fuses would cut off power to customers whenever they detected fault current, even if the cause was temporary in nature.
Considering the rural nature of our service territory, and with storm severity and frequency increasing, outages were creating reliability issues, which affected customer satisfaction. Because our crews must travel to each outage location to replace a blown fuse, these incidents also affected operations and maintenance (O&M) costs because of frequent truck rolls (Figure 1). To address these issues, we felt reevaluating our lateral-protection strategy could be valuable.
Our team exploring an advanced lateral-protection solution was familiar with S&C’s TripSaver II Cutout-Mounted Recloser, having deployed it on some laterals to replace aging assets and reduce O&M expenses. Confident in the TripSaver II recloser’s proven effectiveness, the team decided to expand its role to address fuse-protected laterals. By bringing fault-testing to the lateral level, the TripSaver II recloser could prevent temporary faults from becoming sustained outages.
We analyzed comprehensive outage reports and reliability indices to identify the best locations for installing the reclosers. The team then deployed our first test case of 20 TripSaver II reclosers in the greater Birmingham area.
After a year in the field, we studied the reclosers’ performance and measured the results. This evaluation showed outstanding reliability improvements. The company saved 106,947 customer minutes of interruption and avoided $15,570 in truck roll costs. The data demonstrated TripSaver II reclosers could improve our system and remove expenses.
“The success of the pilot gave us confidence in the incredible opportunity to reduce O&M costs and improve customer satisfaction,” said Chris McClain, Alabama Power’s grid transformation supervisor. “The team rallied together and developed a very effective game plan and workflow that has allowed us to meet the challenges, track our progress, and achieve our goals.”
The results motivated the team to use TripSaver II reclosers to accelerate our grid-modernization efforts and improve customer experience across our service territory. To make the most efficient upgrades possible, we developed a suite of tools called Grid Inform, which uses data analytics to help identify and prioritize potential projects. The tool considers a range of data inputs, such as worst-performing feeder ratings, lost revenue from frequent outages, the impact of truck rolls on O&M costs, and vegetation-management costs.
We were able to combine multiple data sets to build a robust data-analytics tool to evaluate our system and help us prioritize the most strategic investments. It gave us targeted locations to install TripSaver II reclosers. The data have shown how these lateral reclosers have quickly improved our system for our customers while also providing incredible O&M savings. They are now a core part of our grid-modernization plans.
The Grid Inform tool targeted areas of our service territory that would benefit the most from a change in lateral-protection strategy and investment in new technology. The next step was an expanded deployment of approximately 100 TripSaver II reclosers throughout various parts of the state, supported by additional data analytics. Using the Grid Inform tool, we selected locations that replaced first-line protective fuses on laterals with TripSaver II reclosers.
After analyzing the results in the field for two years, we found the 100 deployed TripSaver II reclosers registered significant improvements for both the company and our customers. As storms and wildlife pressured the system, our data revealed 71% of faults were temporary, and the reclosers prevented these faults from becoming sustained outages. We also included major event days in our evaluation to better track customer satisfaction and O&M cost savings during both blue-sky days and severe weather.
“Our strategic deployment of the TripSaver II reclosers has proven to reduce operating costs and improve reliability, bringing benefits both to our customers and our stakeholders,” said Alabama Power Principal Engineer David Boyd. “Temporary faults, such as squirrels and small limbs, make up a large portion of our outages. By installing TripSaver II reclosers in targeted locations, the company has been able to reduce these outages, resulting in fewer unnecessary, costly truck rolls and a reduction in customer outages.”
As a result, laterals protected by TripSaver II reclosers went from experiencing an average of 2.1 sustained outages to 0.47 sustained outages per year. The real-world impact for customers meant these households went from experiencing a sustained outage more than twice a year to once every three years. The installation resulted in a 70% improvement in our System Average Interruption Frequency Index (SAIFI) and a 57% improvement in our System Average Interruption Duration Index (SAIDI) where TripSaver II reclosers were deployed.
“The TripSaver II recloser has both reduced customer outages and created long-term O&M savings,” said Eastern Division Operations Manager Brian Doyle. “The Alabama Power data-analytics team used historical information to identify locations with frequent sustained faults, and the TripSaver II recloser was installed in place of existing fused cutouts. The upgraded sectionalizing of the TripSaver II recloser has improved reliability, reduced callouts, and improved our customer’s experience.”
Because of the results from this targeted program, we confidently developed a strategic grid-modernization program that involved installing TripSaver II reclosers throughout the state. Next, we embarked on our modernization program, which involved deploying approximately 1,500 of the reclosers per year over 10 years. The number of TripSaver II reclosers is expected to increase annually as we continue to see impressive results. Alabama Power presently has more than 4,000 TripSaver II reclosers that have positively impacted thousands of customers and eliminated more than 6,000 interruptions annually.
“In addition to increased reliability and lower O&M costs, our use of the TripSaver II recloser has had a positive operational impact,” said Alabama Power Distribution Control Center Manager Chad Parks. “Every saved truck roll equates to one less incident that must be managed by Distribution Control Center personnel. That also means fewer incidents that require switching to be performed by field personnel and system operators. As we seek to reduce the exposure to critical risks, we count that as a win in terms of safety for our employees.”
With every TripSaver II recloser installed, the Grid Inform tool captures more data. Our team analyzes the information to strategically deploy the TripSaver II recloser throughout our grid to ensure the maximum benefit to our customers. The tool also enables us to gain a deeper understanding of our system and find the most efficient path to advance our overall system capabilities through broader grid-modernization efforts.
By leveraging the data and capabilities of the TripSaver II reclosers, this widescale deployment is helping us improve reliability and prevent unnecessary truck rolls. Company crews are now free to focus on modernization efforts and prepare our system for the challenges of tomorrow.
—Shane Powell, PE is Data Analytics and Innovation Manager at Alabama Power.