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Press Releases

New line, substation improve reliability, increase capacity of transmission system in the Dakotas

March 2019

Project connects renewable energy from North and South Dakota

ST. LOUIS, Mo. (March 22, 2019) ‒ Otter Tail Power Company and Montana-Dakota Utilities Company are delivering more reliable power to their customers’ homes and businesses, as well as increasing the ability to deliver low cost, renewable energy to the region, thanks to a new transmission line and substation placed into service in February 2019.

The utilities jointly developed the 163-mile-long Big Stone South to Ellendale (BSSE) 345 kV transmission line, one of the biggest transmission projects they have ever undertaken. The line will increase the utilities’ capacity to deliver electricity generated by renewable energy in the region, which ranks among the top in the country for wind energy potential. It also strengthens the connections of the local grid to the larger grid that spans across the region.

The BSSE line mostly follows a stair-step route along existing county and township roads from the Big Stone South Substation near Big Stone City, South Dakota, to the Ellendale Substation near Ellendale, North Dakota.

The utilities called on POWER Engineers Incorporated (POWER) to provide engineering services including routing and permitting support, design criteria development, preliminary structure spotting, electrical studies and project cost estimating, among others. POWER also provided expert witness testimony before the South Dakota Public Utilities Commission in order to obtain the regulators’ approval. With those steps completed, the utilities hired POWER as their primary transmission engineer.

POWER’s line design helps overcome the problems of aeolian vibrations and ice galloping, created by prairie winds, that can cause damage to wires and hardware, as well as pull down poles, trip circuits and cause outages. Obtaining soil borings at each structure location helped POWER determine the optimal structure and foundation dimensions, providing opportunities for the utilities to save on construction costs.

“Work on the BSSE project went about as smoothly as any project can,” said Danny Frederick, POWER’s project engineer for BSSE. “We’re pleased to have been a part of this important project to improve reliability and increase capacity of the electric system.”