SAIDI (System Common Interruption Period Index) and SAIFI (System Common Interruption Frequency Index) are extensively used reliability indices that measure the efficiency of energy distribution methods.
SAIDI represents the overall length of interruptions for a mean buyer over a given time interval, sometimes a 12 months. It’s calculated by taking the sum of all buyer interruption durations and dividing it by the overall variety of clients served. The unit of measure for SAIDI is minutes of interruption per buyer. A decrease SAIDI worth signifies higher reliability, because it means clients skilled shorter complete outage durations on common.
SAIFI, in the meantime, denotes the typical variety of sustained interruptions skilled by a buyer over a given time interval, additionally sometimes a 12 months. It’s calculated by taking the overall variety of buyer interruptions and dividing by the overall variety of clients served. The unit of measure for SAIFI is energy interruptions per buyer. A decrease SAIFI worth signifies higher reliability, because it means clients skilled fewer interruptions on common.
These indices permit utilities to quantify and benchmark the reliability of their distribution networks. Regulatory authorities typically use SAIDI and SAIFI targets to incentivize utilities to keep up and enhance reliability. The indices assist determine weak areas within the community that would profit from upgrades or upkeep to cut back the frequency and length of outages.
The U.S. Power Info Administration (EIA) experiences SAIDI and SAIFI values in its Electrical Energy Annual report, which is recurrently launched in October every year. In the latest report, the U.S. distribution system’s common SAIDI worth together with all occasions was 335.5 minutes per buyer in 2022. If main occasion days had been excluded, which is commonly a worthwhile train to get correct long-term tendencies as a result of hurricanes and extreme winter storms, for instance, can skew the numbers fairly dramatically in a given 12 months, the determine dropped to 125.7 minutes per buyer. Notably, this the best SAIDI worth tallied previously decade and it continued what has successfully been a gradual year-over-year decline in efficiency from 2013 by 2022. (2017 noticed a quick enchancment over 2016, however yearly earlier than and since has been worse than the earlier 12 months through the timespan coated by the report.) For comparability, in 2013, the SAIDI worth was 106.1 minutes per buyer.
SAIFI values don’t range as noticeably as SAIDI, however nonetheless have been worsening. In 2022, the U.S. distribution system’s common SAIFI worth together with all occasions was 1.4 energy interruptions per buyer. With main occasions excluded, SAIFI was 1.1 interruptions per buyer within the U.S. Whereas this was not considerably worse than values reported in different years over the previous decade (yearly from 2013 onward has been 1.0, aside from 2016 when the worth was additionally 1.1), it appears to substantiate that the system hasn’t been enhancing.
But, Mike Edmonds, Chief Industrial Officer for S&C Electrical Firm, mentioned a number of issues may be executed to enhance the reliability and resiliency of the facility distribution system. “The grid appears totally different relying on what state you’re in,” Edmonds mentioned as a visitor on The POWER Podcast. “We’ve bought nice expertise with Florida Energy & Gentle [FPL],” he mentioned. “We’ve helped them create a resilient grid. So, that’s not solely a grid that’s dependable, however a grid that may truly climate the storms and all of the challenges thrown on the grid.”
Notably, FPL reported in March that it had supplied “probably the most dependable electrical service in firm historical past in 2023.” Over the previous 20 years, FPL mentioned its clients have realized a exceptional 45% enchancment in reliability (Determine 1). In NextEra Power’s (the guardian firm of FPL) Sustainability Report 2023, the corporate reported FPL’s SAIDI was 47.1 and SAIFI was 0.85, confirming markedly higher outcomes than the U.S. averages famous earlier. Moreover, FPL mentioned that is the ninth time previously 10 years that it achieved “its best-ever reliability score.”
“FPL is dedicated to delivering exceptionally dependable service to our clients whereas protecting payments as little as potential,” FPL President and CEO Armando Pimentel mentioned in an announcement issued on March 1. “In fact, we dwell in a state with more and more extreme climate and a year-round rising cycle, so reliability is each high of thoughts and all the time a problem. And, that’s what makes our reliability story much more exceptional—we’re placing the stability between efficiency and value. Our good investments and ongoing efforts to strengthen the grid are making an actual distinction for our clients.”
“Very often, we hear the {industry} discuss nearly solely round transmission—and it’s extraordinarily essential—however you’ll be able to have an ideal transmission grid, however you’re nonetheless not going to have a resilient grid until you’re truly taking the grid all the best way to the purpose of consumption,” mentioned Edmonds. “And actually, that’s what Florida Energy & Gentle has executed a extremely glorious job of over the past 10 years.”
Among the many issues FPL has executed to harden its power grid are:
- Putting practically 2,000 neighborhood energy strains underground because the inception of its Storm Safe Underground Program in 2018.
- Putting in greater than 215,000 clever gadgets alongside the grid. This good grid expertise detects and prevents energy outages and minimizes restoration instances when outages do happen. The expertise has helped keep away from greater than 13 million outages since 2011.
- Inspecting energy poles and changing those who not meet industry-leading requirements.
To raised perceive a few of the revolutionary new tools S&C Electrical Firm provides, Edmonds supplied an instance. “We now have some expertise that does one thing referred to as ‘pulse discovering,’ and what Florida Energy & Gentle does, it simply lets our tools do what it does greatest. If there’s an issue, it’ll pulse to see if the issue is there or not on the grid, if it’s not, it reenergizes,” he mentioned. “This expertise is on the market to essentially change how the grid operates.”
Edmonds mentioned S&C Electrical Firm invented the fuse 115 years in the past, and he famous fuses have served the {industry} properly since that point. Nonetheless, immediately there may be higher expertise obtainable that doesn’t require a lineworker to answer an outage to switch a fuse. “Let’s take fuses off the grid and have a fuseless grid, and have far more clever gadgets that may truly re-energize,” Edmonds decreed.
To listen to the total interview with Edmonds, which incorporates extra about expertise obtainable to enhance energy grid efficiency, take heed to The POWER Podcast. Click on on the SoundCloud participant under to hear in your browser now or use the next hyperlinks to achieve the present web page in your favourite podcast platform:
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—Aaron Larson is POWER’s government editor (@AaronL_Power, @POWERmagazine).
