Electric energy and environment: Some technological challenges in Brazil

Brazil is a country with huge unexplored hydraulic reserves, principally in the Amazon region, that are more than 2000 to 3000 km from the consuming centers. However, the Amazon region has serious environmental concerns, which are imposing many technical challenges. In this chapter, some of the studies being developed at our university with the objective of overcoming these challenges and allowing good use of this renewable energy source with minimum environmental impact is presented. If conventional alternate current (ac) transmission systems were used for these long distances, important severe drawbacks would occur, mainly in relation to the distance, which causes line network behavior quite different from that of lines of the usual length. To overcome this problem, an ac transmission line of little more than half wavelength without fixed reactive compensation bht with a small active compensator is proposed to produce a transmission line with excellent performance and low cost per line length. In addition, optimized conductor distribution configuration is being studied to minimize the areas where trees must be cut for the line passage. The de transmission system is also analyzed, and in this case the unit connected generator/HVDC thigh voltage de system) converter is studied with the objective of minimizing cost as well as maximizing hydraulic turbine efficiency. Also, the possibility of supplying small amounts of power to small communities living near the transmission lines using small HVDC taps based on a high-frequency self-commutated converter is analyzed. Both the unit connection and the small taps have shown to be very interesting solutions for actual applications.