The connection between modal analysis and electric torque analysis in studying the oscillation stability of multi-machine power systems

Modal analysis and electric torque analysis are two of the most widely used techniques for studying the oscillation stability of multi-machine power systems, such as for the design of Power System Stabilizers (PSS) or FACTS-based stabilizers. Modal analysis is based on modal control theory and electric torque analysis is established and developed from a physical understanding of the characteristics of the electromechanical oscillation loop of generators in power systems. These two techniques have been considered to be different both in their principles of derivation and methods of calculation. However, in this paper, a connection between these two methods is revealed. It is found that they are basically equivalent. Through the revelation of the connection between these two methods, a deeper insight and understanding into the mechanisms of the methods is presented in the paper. (C) 1997 Elsevier Science Ltd.