Outage reduction goal crushed by 20 minutes
To be in the top third lowest outage times among electric cooperatives, a co-op must have a system average interruption duration index (SAIDI) score of 78 or less; OEC recently scored a remarkable 67 among distribution co-ops, placing us well below the average score of 126 among National Rural Electric Cooperative Association electric co-ops nationwide. The Oklahoma Corporation Commission reported investor-owned utility scores ranging from 100 to 158 in 2016. When considering Western Farmers Electric Cooperative (WFEC, OEC’s wholesale power provider) outage times, OEC’s score is 84.
What exactly is a SAIDI score and why does it matter? SAIDI measures the average minutes a member is out of power in a given year. Because the goal is to keep the lights on, a lower number indicates a better score.
The SAIDI score reflects a system average outage time, which means some substations and feeders perform more efficiently than others. A 2017 strategic initiative set by OEC's board of trustees allowed OEC to identify, plan and address the worst performing substations and circuits and provided the resources to eradicate the issues.
“I believe our system hardening initiative had a major impact,” said Nick Shumaker, manager of system engineering. “We emphasized the much needed upgrading of our lightning protection equipment, which has played a large role in reducing our outage time.”
In 2016, 29,370 lightning strikes across OEC’s service area accounted for 30 percent of the outages — Oklahoma is the second most lightning prone state behind Florida. Because of these system-wide improvements, outages caused by faulty equipment dropped by 35 percent from 2016 and accounted for a SAIDI score reduction of seven minutes on its own.
“We focused on improving the three feeders that had the highest outage times in 2016,” said Shumaker. “Those included one feeder from the Cole substation that serves Washington, Goldsby and Dibble, one feeder from the Noble substation and one from the Tuttle substation.”
Each feeder experienced a drastic drop in outage times — a 51 to 86 percent reduction. The outage time in 2017 for members in Noble dropped by 198 minutes per person. Members in Tuttle had the lowest outage time of any feeder in 2017 — only 13 minutes per person.
Members system-wide experienced a total reduction in outage time of 430,514 minutes, which translates to a SAIDI reduction of 7.7 for the entire system.
“We continue to focus on improving and upgrading our equipment in the field as much as our budget allows,” said Shumaker. “We implemented an insulator change-out program over the last year. Before that, we never had a systematic way of inspecting and replacing insulators or lightning arrestors, which are critical because they are made to take damage from lightning and are difficult to visually inspect from the ground.”
All of this translates to an improved electric system that provides incredibly reliable service on a consistent basis for all 42,000 members.