Concepts of synchronous machine stability as affected by excitation control

Abstract-The phenomena of stability of synchronous machines under small perturbations is explored by examining the case of a single machine connected to an infinite bus through external reactance. The analysis develops insights into effects of thyristor-type excitation systems and establishes understanding of the stabilizing requirements for such systems. These stabilizing requirements include the voltage regulator gain parameters as well as the transfer function characteristics for a machine speed derived signal super-posed on the voltage regulator reference for providing damping of machine oscillations