Quantifying proximity to voltage collapse using the Voltage Instability Predictor (VIP)

In previous work concerning the Voltage Instability Predictor (VIP), the proximity to voltage collapse (or instability) was expressed in terms of distance between two voltage curves or between two impedance curves. In this paper, a new measure, power margin, is introduced to describe the proximity to collapse in terms of power. The results of work on the effects of contingencies and system dynamics on the VIP are also presented, extending the prior work that assessed the effectiveness of the VIP under conditions of increased power transfers, using power flow simulations to examine voltage collapse conditions. These results show that the VIP algorithm successfully predicted voltage instability where conventional protection devices, using only voltage inputs, did not.