Rio Madeira, World's Longest Transmission Link

At 2,375 kilometers in length, the Rio Madeira high-voltage direct current (HVDC) transmission system is an impressive feat of South American electrical engineering. Beating the second-longest transmission link - the 2,090 km Jinping-Sunan link in China - by almost 300 km, the Rio Madeira link was brought online in November 2013, taking two years to complete.

[Image source: ABB]

With the highest housing density in Brazil's population of over 200 million, power demands in the São Paulo region are high. While well below the global per capita household electricity use average of 3,500 kWh per year , meeting Brazil's 2,500 kWh per capita average requires a way to link the main power sources available to the places it is most needed.

Brazil depends almost exclusively on hydroelectric power for its electricity, with a massive 95 percent of electric power sourced from hydropower plants. The Rio Madeira transmission system links two Madeira River hydropower plants (the Santo Antônio and Jirau) in Brazil's equatorial northwest to the major load centers in temperate south-eastern São Paulo.

[Image source: ABB]

Alternatives to the final HVDC transmission technology were considered to ensure optimal outcomes for the project. High-voltage alternating current (HVAC) and HVDC-HVAC hybrid systems in various configurations were considered. The project team encountered restrictions in supporting full load rejection when using very long HVAC radial transmission systems above 1,500 kilometers. HVDC was found to be the option with the least amount of risk.

For those who like system specs (and you know you do), here's a neat table of the main data:

[Image source: ABB]

Key technology for the Rio Madeira link cost over half a billion dollars, including transformers like you have never seen. Check out this clip of how the seven 400 ton, 600 kV HVDC transformers were transported from Scandanavia to the Amazon:

The transmission link is capable of transmitting 7.1 GW of power to populous São Paulo, on par with other massively long HVDC transmission links around the world.

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