Brazilian North-South Interconnection control-application and operating experience with a TCSC

This paper aims at presenting part of the results of field tests performed in order to put a thyristor controlled series compensation (TCSC) in commercial operation in the Brazilian North-South Interconnection. It also presents a summary of the background that supported the task of locating and designing a TCSC to damp the North-South low frequency inter-area oscillation mode. It deals with a pioneer commercial TCSC application in a very important step of the Brazilian power system expansion. The North/South Interconnection, a single 500 kV compact transmission line (4×954 MCM bundle), 1020 km long, was energized at the beginning of 1999 and has been in reliable operation since then. It is dimensioned to transmit up to 1300 MW, with suitable operation being required from no load up to maximum flow in both directions. A TCSC control system suitable for transient and dynamic stability analysis was designed and, together with extensive study results, formed the basis for the equipment specification and its location along the interconnection. The utilization of two small TCSCs (6% compensation each) proved to be very effective in damping the poorly-damped 0.2 Hz inter-area mode. This paper focuses on the TCSC installed at Imperatriz, a substation in the North system (Eletronorte system). The tests performed during the commissioning clearly confirmed the effectiveness of the TCSC in damping the power oscillations