Abstract

In this paper an analysis of the voltage collapse phenomenon in longitudinal systems is presented. The analysis is performed through a small signal perturbation approach where the nonlinear multimachine dynamic model is linearized around a steady-state operating point, and the stability of the system is evaluated through the eigenvalues of the Jacobian matrix of the dynamic state equations. The analysis clarifies the difference between the maximum loadability point and the voltage stability limit. In addition, a voltage collapse proximity indicator, taking into account the dynamic of the system, is proposed and tested in three different networks.