Since spring of 1999, Eletronorte of Brazil has been operating a Thyristor-controlled Series Capacitor (TCSC) and five fixed Series Capacitors supplied by Hitachi Energy in Eletronorte´s 500 kV interconnector between its northern and southern power systems. All in all, about 1.100 Mvar of series capacitors have been installed by Hitachi Energy. The TCSC is located at Imperatriz at the northern end of the power corridor connecting the two systems which were previously not interconnected.
Feasibility studies had been performed regarding the interconnection of the two systems, and a decision was made to go ahead and build the transmission corridor. Both AC and DC alternatives were assessed, and decided in favour of the AC option. It consists of a single 500 kV compact circuit (subsequently doubled), more than 1.000 km long and series compensated in several places along the line. Operation began in 1998. The power transmission capability of the corridor is 1.300 MW.