A Second Order Indice for Estimating Voltage Stability Margin Based on Analytic Thévenin Equivalent

In estimating the long term voltage stability of power system, the linearity and accuracy of indice is important. In this paper, a second order indice based on analytic Thévenin equivalent (TE) is proposed for estimating static voltage stability margin. Its analytic expression only using single instant wide area measurements, which make it not be affected by the system inside power change. As a second order indice, its linearity performance well. Compared to conventional voltage stability indice (VSI), such as impedance modulus, the proposed indice has better linearity feature, which can support operators to estimate the remaining power effectively. The performance of proposed VSI is verified on both IEEE 118-bus system and Alberta 2016-bus system.