CONDITIONS FOR SADDLE-NODE BIFURCATIONS IN AC DC POWER-SYSTEMS/

Saddle-node bifurcations are dynamic instabilities of differential equ ation models that have been associated with voltage collapse problems in power systems. This paper presents the conditions needed for detect ing these types of bifurcations using power flow equations for a dynam ic model of AC/DC systems, represented by differential equations and a lgebraic constraints. Two methods typically used to detect saddle-node bifurcations, namely, direct and parameterized continuation methods, are briefly analysed from the point of view of numerical robustness.