Embedding AC Power Flow in the Complex Plane Part II: A Reliable Framework for Voltage Collapse Analysis

Abstract: Part II of this paper elaborates on the unique capability of the proposed power flow analysis framework to obtain the true solution corresponding to the stable operating point of a network. It explains the significance of obtaining the true solution for an accurate assessment of the voltage collapse margin. This feature distinguishes the framework from all iterative and non-iterative heuristic approaches as demonstrated in the context of a 7-bus network with Newton-Raphson, its variants and semidefinite and moment-based relaxations of power flow. Another important feature of this framework is that it obtains the true solution when it exists and declares its non-existence otherwise. This is demonstrated in the context of small networks and in comparison with heuristic approaches. This paper also explores how the proposed framework detects a limit-induced bifurcation where a network controller reaching its limit can initiate voltage collapse.