Determination of the applicability of using modal analysis for the prediction of voltage stability

The development and use of accurate methods to predict incipient voltage instability is crucial in preventing such voltage collapse situations. A comparison of the common steady-state methods for voltage stability analysis was undertaken, along with a brief examination into the dynamic approach. Special attention is given to modal analysis technique which provides both a relative proximity of the system to instability, as well identifies the key contributing factors to instability. A PC-based MATLAB prototype application was developed to assist power system operators in the assessment and analysis of the voltage stability of a power network, at any given operating point. Using modal analysis technique, useful features such as power flow analysis and traditional V-P/V-Q analysis have been incorporated. Using the IEEE 30 bus system, the modal analysis technique was shown to provide an accurate estimate of the system´s proximity to the voltage stability limit, and to consistently and correctly predict the critical buses and the weakest branches in the transmission system.