When Bipole 1 commenced commercial operation in 2014, Rio Madeira became the world’s longest HVDC line, surpassing the Xiangjiaba–Shanghai system in China.

These have very low inertia compared to other types of hydro-electric generator, and this led to concerns that the turbines could be damaged by over-speed in the event of a sudden interruption to power transmission on the HVDC lines.

This option was divided into seven separate packages, referred to as Lots 1–7:[1] The transmission voltage of ±600 kV is the same as was used on the Itaipu project, but for Rio Madeira the converters are designed with only a single twelve-pulse bridge per pole.

[3] The design of certain aspects of the two bipoles (which were supplied by different manufacturers) needed to be coordinated in order to avoid adverse control interactions or harmonic filtering problems.

In addition, a considerable number of different operating modes needed to be taken into account, such as paralleling the converters of both bipoles onto a single transmission line.