Brazil-Argentina HVDC Interconnection
Garabi HVDC back-to-back station

HVDC > HVDC References > South America > Garabi

The ABB HVDC CCC concept made it possible to avoid building a synchronous compensator plant at Garabi.

Each of the two 1100 MW phases of the Garabi HVDC back-to-back converter station is divided into two blocks of 550 MW each. The first phase went into commercial operation in 1999 and the second phase in 2002.

The time schedule for the completion of the first phase of this HVDC interconnection, from signing of the contract between CIEN and ABB, to commercial operation, was only 22 months, a significant challenge for a project of this magnitude. This has required considerable innovation in manufacturing and construction techniques for both the transmission lines and converter station.

Each line to from Garabi to Itá has a length of 354 km, quite challenging for operation of a converter station where there is guaranteed delivery of 1000 MW into a rather weak point. For the chosen transmission line parameters, the short circuit capacity at the Garabi 60 Hz side is about 1500 MVA, dropping even lower under contingency conditions.

Commutation capacitor

This challenge was met by using the CCC concept and with minimum sized ConTune harmonic filters. In this way fixed line reactors are used and the CCC means that the converter has characteristics to absorb or supply reactive power as required by the system. The converter acts like a static compensator, giving smooth continuos control of voltage and power flow. The minimum size of

the ConTune filters helps to keep load rejection overvoltages within limits.

Overview of the HVDC station at Garabi		Outdoor HVDC valves

The HVDC converter valves are in modular housings, factory assembled and tested and shipped to site ready for operation. The control equipment and auxiliaries are similarly factory assembled and tested, reducing the installation and commissioning time. With this type of arrangement a considerable area reduction could also be achieved.

All converter bus breakers are of the modular Compact type with breaker, disconnects, and optical current transformer (OCT) integrated in one unit. The Compact breaker can be quickly installed or removed, allowing efficient maintenance as well as facilitating future changes in sub-station layout due to planned expansion.

Main data
Commissioning year:	First phase 2000, Second phase 2002
Power rating:	2 200 MW
No. of circuits:	4
AC voltage:	500 kV (both sides)
DC voltage:	± 70 kV
Type of link	Back-to-back station with CCC
Main reason for choosing HVDC:	Asynchronous link between a 50 Hz and a 60 Hz system