Construction will start immediately on an emergency replacement of the Ramsey-McHenry 230 kv transmission line, Great River Energy's only alternating current (AC) transmission line in North Dakota, the Minnesota cooperative said Friday.
Great River Energy notified the North Dakota Public Service Commission (PSC) of its declaration of a power emergency with regard to its Ramsey-McHenry 230 kv line that was leveled by straight line winds Aug. 12. Sixty-eight of its structures were destroyed in the storm.
Construction of the temporary line should be completed over the next several weeks, Great Rivers said.
Although the Mid-Continent Area Power Pool initially said loss of the line would not significantly affect the interconnected system, subsequent load flow models showed the situation is more precarious than once believed.
In the blizzard of 1997, Great River Energy's 230 kv line was "holding North Dakota together" after two 345 kv lines went down, says Kandace Olsen, a cooperative spokeswoman. She said after talking with other utilities in the region and with winter storm warnings up, "we felt the situation was tenuous. What if it happened again?"
Work on the power line gets under way as stretches of the upper Midwest are covered by snow or severe winter storm advisories, with several inches of snow expected in Minnesota and North Dakota. The National Weather Service is warning of white out conditions and the potential for "dangerous wind chills" in the region Monday
The 260-mile long Ramsey-McHenry line originates in Stanton and terminates in Grand Forks, ND. It provides a transmission path from the coal field generation to Devils Lake, Minot, and Grand Forks, ND. It also helps stabilize the electric transmission grid in and outside of North Dakota.
The temporary line will remain until a new, permanent line can be constructed. Great River Energy said it proposes to reroute further north those sections of the line that crossed through the water in Devils Lake. A spokesman for the North Dakota PSC said due to high water "the poles keep falling over" in the lake.
The temporary line will be 10.25 miles long. It will utilize existing right-of-way for the most part, but will require 2.7 miles of new right-of-way. Great River said engineers believe they can design the line so airport traffic will not be disturbed and are working closely with the Devils Lake Airport Authority.
After the storm, Great River Energy, along with neighboring utilities Xcel Energy, Otter Tail Power Co., Minnkota Power Cooperative, Basin Electric Power Cooperative, Montana Dakota Utilities, and Manitoba Hydro, worked together to rewrite operating guides for the central North Dakota system.
Theses new guidelines included utilizing load management, redispatching generation, installing special equipment on the power lines, and setting automatic tripping devices on some power plants to prevent voltage collapse and thermal overload of the system.
But the measures were not enough resolve the problem, Great River said. The Elk River, Minn-based cooperative said a final route has not yet been determined, but the goal is to have the new permanent line constructed by the winter of 2001.
Minnesota's second largest utility in terms of generation capacity, Great River Energy supplies electric and related services to 29 distribution cooperatives in Minnesota and Wisconsin. It owns and operates two power plants in North Dakota: the 1,081 Mw Coal Creek station near Underwood and the 186 Mw Stanton station.