Abstract

Power system voltage stability may be defined as the ability of a system to maintain load voltage magnitudes within specified operating limits under steady-state conditions. When this ability is lost, the system experiences severe drops in its voltage profile. If the load increases, the network may suffer a general drop in voltage, leading to the so-called voltage collapse. An important family of methods evaluate the proximity of a network to the voltage collapse by calculating the least eigenvalue of the Jacobian matrix of the system. In this paper, a method that performs an estimation of the least eigenvalue of the Jacobian matrix of the system is presented. The electrical network is divided into several subnetworks according to a coherency criterion and the estimation is accomplished by tracking the least eigenvalue of the subnetwork closest to the voltage collapse.