The Argentina - Brazil HVDC interconnection, owned by Cien/Endesa Group, demonstrates the advantages of the modular HVDC back-to-back interconnection concept in a project designed to encourage cross-border energy trading between the two countries.
The transmission system comprises 490 km of 500 kV AC overhead lines between the two substations of Rincón de Santa Maria in northern Argentina and Itá in southern Brazil, and an HVDC converter station at Garabi in Brazil, near the border.
Argentina's power system operates at 50 Hz, and Brazil's operates at 60 Hz. The asynchronous interconnection is through HVDC frequency converters in a back-to-back configuration at Garabi.
ABB's capacitor commutated converter (CCC)-type HVDC converter technology made it possible to avoid building a synchronous compensator plant at Garabi. Each of the two 1,100 MW phases of the Garabi back-to-back station is divided into two blocks of 550 MW each. The first phase went into commercial operation in 1999, the second phase in 2002.
A CCC/ConTune combination in the converters enables secure operation at low short circuit levels, improving reactive power control and providing even and continuous voltage and power flow control. The converter station's modular construction concept simplifies civil design and ensures an environmentally acceptable solution and shorter delivery time.
Each line from Garabi to Itá in Brazil is 354 km long, a challenge for a converter station that guarantees delivery of 1,000 MW into a rather weak point of the grid.
This cross-border system enables both countries to utilize electricity resources more efficiently and cost-effectively, increasing system reliability and enabling secondary energy trades. The time schedule for completion of the first phase was only 22 months, a significant challenge for a project of this magnitude.