Bipole lines

Manitoba Hydro is known around the world for our development of transmitting high-voltage direct current (HVDC) electricity over long distances.

HVDC transmission helped untap the tremendous hydroelectric potential of the Nelson River in the 1960s, bringing electricity produced by generating stations on the river to southern Manitoba.

The Nelson River HVDC transmission system includes 3 lines called Bipole I, Bipole II, and Bipole III. Bipole refers to the positive (+) pole and a negative (−) pole which allows electricity to travel great distances without much loss of power.

Before Bipole III’s completion in 2018, over 70% of electricity generated in Manitoba was delivered to customers through Bipole I and Bipole II.

These 2 transmission lines run alongside each other for much of their 895-km route, starting at the northern Radisson and Henday converter stations near Gillam. Both lines end in the south at the Dorsey Converter Station just northwest of Winnipeg.

Because of their proximity to each other, a severe weather event could damage Bipole I and Bipole II at the same time. This would have left us unable to transmit enough electricity to meet demand, and result in extended outages and potential blackouts.

Manitoba Hydro crew in a grass field build a new bipole tower on the ground.

In 1996, high winds knocked down 19 towers on Bipoles I and II. For the first time in history, Manitobans were asked to reduce their non-essential power consumption while the towers were fixed over 4 days — they responded with an 8% reduction.
Enlarge image.

The Bipole III HVDC transmission line has a total of 3,078 towers erected on a different route through western Manitoba and two new converter stations. It begins at the Keewatinohk Converter Station approximately 80 km northwest of Gillam, and ends at the Riel Converter Station just east of Winnipeg.

Bipole III provides 2,000 MW of additional capacity, and an independent and physically separate HVDC system. This significantly reduces the impact severe weather events may have on the HVDC system in the future, and increases the reliability of delivery of electricity to our customers.

  • Voltage
    • Bipole I: 900 kV (±450,000 nominal, ±463,000 maximum);
    • Bipole II: 1,000 kV (±500,000 maximum);
    • Bipole III: 500 kV.
  • Length of lines
    • Bipole I: 895 km;
    • Bipole II: 937 km;
    • Bipole III: 1,400 km.