Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Lane Department of Computer Science and Electrical Engineering

Committee Chair

Muhammad A. Choudhry.


A steady state analysis is applied to study the voltage collapse problem. The modal analysis method is used to investigate the stability of the power system. Q-V curves are used to confirm the obtained results by modal analysis method and to predict the stability margin or distance to voltage collapse based on reactive power load demand. The load characteristics are considered in this research. Different voltage dependent loads are proposed in order to be used instead of the constant load model. The effect of induction machine load is considered in this study. The load is connected to several selected buses.;The analysis is performed for three well-known system; Western System Coordinating Council (WSCC) 3-Machines 9-Bus system, IEEE 14 Bus system and IEEE 30 Bus system. The modal analysis technique is performed for all systems using the constant load model, the voltage dependent load models and induction machine load model. Then, the most critical mode is identified for each system. After that, the weakest buses, which contribute the most to the critical mode, are identified using the participation factor. The Q-V curves are generated at specific buses in order to check the results obtained by the modal analysis technique and to estimate the stability margin or distance to voltage collapse at those buses.