The transmission grid is an intricate system. At the very second electricity is being used, it must be generated somewhere. And the very second a power line goes down in a storm or trips, the electricity that was moving on that transmission is rerouted to another path.
When there is sufficient transmission infrastructure, this system works well as the remaining lines are able to accommodate the increased loading due a particular outage or outages. Transmission construction is underway and plans are in the works to add additional transmission in western North Dakota to allow for much needed additional capacity on the transmission system. However, until that transmission comes in service, Basin Electric has worked with the regional transmission organization, Southwest Power Pool (SPP), on solutions to help bridge the gap.
In the case of transmission loading relief, that’s where a Remedial Action Scheme (RAS) comes in.
Jeremy Severson, Basin Electric vice president of Transmission, said Basin Electric worked with SPP and Western Area Power Administration for the approval and installation of a Remedial Action Scheme in western North Dakota.
“This RAS is a short-term solution that will help address congestion in western North Dakota and ensure reliable service until the Roundup-to-Kummer Ridge 345-kilovolt transmission line is built and in service,” Severson said. “Before the RAS was in place, we would have needed all the peaking generation in northwest North Dakota to be in operation this summer when the wind in that area isn’t blowing to protect the transmission system during a contingent event. This requirement to serve the peak load that our members require with no exceptions is a pinch point where we needed a solution to make sure electricity remained reliable.”
Philip Westby, Basin Electric manager of Transmission Services, said the RAS, which went into operation on Mar. 1, will help relieve the pinch point.
“The scheme is like a safety net program that is designed to shed load in the region in the event of a specific transmission line outage and which allows the grid to serve the remaining load in the region,” Westby said. “Once the Roundup-to-Kummer Ridge is in service later this year, that will increase the transmission capacity to serve the region, and then when Leland Olds Station-to-Tande is in service, that will bump up the transmission capacity once again.” Read more about Roundup-to-Kummer Ridge and Leland Olds Station-to-Tande in the Transmission section of basinelectric.com.
Why is the capacity so tight? The answer comes down to load growth in Basin Electric’s membership and transmission line ratings. A transmission line’s rating, or the “capacity” of electricity it can carry, is reduced during warmer months because hotter temperatures can cause transmission lines to sag more than they do normally with the heat of electricity moving through; pair a sagging line with windy conditions and the potential for outages increases.
Severson said it’s important to note that transmission is very resilient. “The transmission line that we are most concerned about in this area has only tripped once, and that was in 2016 during a thunderstorm,” he said. “Many of our transmission lines have above a 99% availability, but we have to plan for that single outage that could be very troublesome. This temporary RAS helps provide some margin on the system by tripping load during those very infrequent events.”
