CU (Powerline)

CU is the designation of a line for high voltage direct current (HVDC) transmission between the Coal Creek Station power plant south of Underwood, North Dakota at 47°22′24″N 101°9′23″W and the Dickinson converter station near Rockford, Minnesota at 45°06′40″N 93°48′36″W.

The designation most likely refers to two Minnesota-based power generation/transmission cooperatives that originally partnered to build the Coal Creek plant and associated line - Cooperative Power Association and United Power Association, which later merged to become Great River Energy.

The CU project controversy in 1978 and 1979 was a result of protests by farm landowners in the path of the CU line right of way.

The CU line, which went in service in 1979, can transfer an electrical power of 1,000 megawatts at a symmetrical transmission voltage of 400 kV. An overhead line connection 426 miles (710 kilometers) long is used, with two conductors per pole. As is the case in all modern HVDC systems, thyristor static inverters are used.

Crossing of HVDC powerlines

Southwest of Wing, North Dakota, at 47°02′48″N 100°05′49″W CU crosses Square Butte, another HVDC powerline. This is the only crossing point of two HVDC overhead powerlines in the Western hemisphere.

CU is the line of towers on the right, crossing the Square Butte line on the left. Near Wing, North Dakota.