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 3000km 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 but 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 dc transmission system is also analyzed, and in this case the unit connected generator/HVDC (high voltage dc 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.

[1]  Narain G. Hingorani,et al.  Power electronics in electric utilities: role of power electronics in future power systems , 1988, Proc. IEEE.

[2]  L. Salazar.  A LOW LOSS SOFT SWITCHING PWM CSI , 1992 .

[3]  H. Nakra,et al.  A Small Series Tap on an HVDC LINE , 1981, IEEE Transactions on Power Apparatus and Systems.

[4]  G. G. Karady,et al.  Continuously regulated series capacitor , 1993 .

[5]  B. J. Baliga,et al.  Power ICs in the saddle , 1995 .

[6]  Fujio Ishiguro,et al.  Development of a large static VAr generator using self-commutated inverters for improving power system stability , 1991 .

[7]  R.W. Menzies,et al.  Small power tapping from HVDC transmission systems: a novel approach , 1997 .

[8]  Mauricio Aredes,et al.  GTO controlled series capacitors: multi-module and multi-pulse arrangements , 2000 .

[9]  N. Christl.  Advanced Series Compensation (ASC) with Thyristor Controlled Impedance , 1992 .

[10]  Edward Wilson Kimbark,et al.  Direct current transmission. , 1971 .

[11]  T. W. Cease,et al.  Development of a /spl plusmn/100 MVAr static condenser for voltage control of transmission systems , 1995 .

[12]  N.G. Hingorani,et al.  Flexible AC transmission , 1993, IEEE Spectrum.

[13]  M. R. Iravani,et al.  Application of GTO voltage-source inverter for tapping HVDC power , 1994 .

[14]  Laszlo Gyugyi,et al.  Understanding FACTS: Concepts and Technology of Flexible AC Transmission Systems , 1999 .

[15]  Edson H. Watanabe,et al.  A Nonlinear Generalized Switching Function Model For SVC And TCSC Devices , 2001 .

[16]  Mauricio Aredes,et al.  Series connection of power switches for very high-power applications and zero-voltage switching , 2000 .

[17]  M. Szechtman,et al.  Integration of small taps into (existing) HVDC links , 1995 .

[18]  Zhe Zhang,et al.  Analysis and control of Yimin–Fengtun 500 kV TCSC system , 1998 .

[19]  Jos Arrillaga,et al.  Factors affecting the commutation reactance of direct connected generator-converter units , 1999 .