Chapter 4 - Small-Signal Stability Analysis in SMIB Power System

Abstract

This chapter investigated the small-signal stability problem in a single machine infinite bus (SMIB) system. Analyses are carried out based on Heffron-Philips model of an SMIB power system. The differential equations of the flux decay model of the synchronous machine are linearized and a state space model is constructed. From the resulting linearized model, certain constants known as the K–constants (K1–K6) are derived, which are functions of machine and system impedances as well as operating point. The state-space model is then used to examine the eigenvalues and to ensure adequate damping of the dominant modes. The method of small-signal stability analysis, based on frequency domain approach, has been explained. The effect of excitation system, the merits and demerits of increasing exciter gain on synchronous machine stability are also shown analytically. The necessary simulation program for calculation of damping torque and the synchronizing torque for different exciter gain have been given.