Avaliação da estabilidade a pequenos sinais em sistemas CA/CC em paralelo

Abstract

In Brazil, the rst DC transmission systems have traditionally been constructed as asynchronous interconnections of CA networks. However, with the start-up of the bipoles associated to the Belo Monte complex, the interconnection will take place in parallel with the AC system of the National Interconnected System. In this dissertation, we present an analysis of DC transmission systems in parallel with AC systems from the perspective of small-signal stability of electric power systems. We present aspects related to linear and nonlinear representation of the DC link controls. The studies are performed using modal analysis techniques for power systems, as well as linear and nonlinear time domain simulations. The small signal theory is used to identify the critical modes of oscillation from the HVDC, in detriment of the stability margin. The simulations show that, in weak electrical systems, characterized by the low short-circuit ratio, a critical mode from the current control mode of the link may be responsible for triggering a voltage instability process.