Contingency screening and ranking method for voltage stability assessment

The paper presents a method capable of selecting contingencies that lead to voltage insecurities. The contingencies are ordered according to their effect on the system operating state. Insecurities are measured by the apparent power margin between the busbar injected power at the operating point under analysis and an estimate of the maximum injection, as well as by the region of operation in the SV curve. The influence index translates the margin reduction after the disturbance. The method allows nodal as well as affected area analysis. The N/NE Brazilian system is used in an illustrative numerical example. Computational time is no burden for real-time operational analysis.