ABB strengthens reliability of U.S. power supply

Zurich, Switzerland, - ABB, the leading power and automation technology group, said today it has successfully commissioned a high-voltage direct current (HVDC) transmission system link, interconnecting the eastern and western power grids of the United States. The back-to-back system is expected to boost grid reliability.

The HVDC system, called the "Rapid City Tie" because it passes close to Rapid City, South Dakota, carries 200 MW of power. ABB completed the US$50 million contract in only 19 months - six months faster than the industry standard.

"The new power transmission system will substantially increase grid reliability in the U.S.," said Peter Smits, head of ABB's Power Technologies division. "Interconnections such as the Rapid City Tie lower the risk of blackouts, because they allow a controlled power flow between otherwise independent power grids."

The HVDC system provides voltage and frequency support in case of disturbances in either of the grids. ABB designed, manufactured and installed the HVDC system as part of the joint project between Basin Electric Power Cooperative of North Dakota, and Black Hills Power of South Dakota.

The high-voltage alternating current (AC) grids in the eastern and western U.S. do not operate synchronously and require a technology interface to connect them. HVDC technology takes the AC from one grid, converts it into direct current, and then re-converts it into AC for the other grid.

ABB pioneered HVDC transmission technology to interconnect power grids.

ABB ( is a leader in power and automation technologies that enable utility and industry customers to improve performance while lowering environmental impact.

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