The 12,600 MW Itaipu generating station, located on the Parana River on the border of Brazil and Paraguay, is jointly owned by Paraguay and Brazil. Half of the Itaipu generators operate at 60 Hz, the frequency of the Brazilian system, while the other half of the generators operate at 50 Hz, the frequency of the Paraguayan system. Most of the 6,300 MW from the 50 Hz generation is transmitted a distance of about 900 km to Sao Paulo using HVDC transmission with two bipolar circuits each rated at ±600 kV, 3150 MW. The remaining 6,300 MW from the 60 Hz generation is transmitted by three 765 kV transmission lines.
Teshmont performed detailed system and design studies and prepared specifications for the Itaipu transmission system project. Teshmont also carried out a “state of the art” study, to establish the most appropriate technology to transmit the power. This was followed by a feasibility study of alternative transmission systems including 500 kV, 765 kV, and 1000 kV ac, as well as ±600 kV dc. A technical and cost study of ac and dc transmission showed that transmission at 765 kV ac was the optimum alternative.
Following a decision to transmit half the power by dc, Teshmont carried out extensive system studies for a combined ac-dc transmission system with 6,300 MW transmission by HVDC and the remainder by 765 kV ac. Teshmont provided assistance with the preparation of converter specifications, tender evaluation, and design review.
Studies Teshmont conducted for this project included:
• HVDC integration studies and planning studies
• Comprehensive load flow and stability studies
• DC simulator studies to determine dc system performance requirements and amount of synchronous compensation/static var device support
• AC and dc filter studies to define acceptable limits of interference
• Overvoltage studies
Teshmont then prepared specifications for all equipment associated with the HVDC system including the converter stations, evaluated tenders, made recommendations to purchase and reviewed suppliers designs.