Linear Analysis and Small‐Signal Stability

Abstract

This chapter presents the small‐signal stability of power systems operating in “steady state,” that is, the system stability of an equilibrium point. The ability of the power system to track the load changes requires the power system to be small‐signal stable, that is, a power system can stably move from one operating condition to a slightly different operating condition. The chapter discusses electromechanical modes in power systems and techniques to compute and identify the frequency and damping of these modes. The approach used is to develop linearized system models that are valid in a region about the equilibrium operating point. Electromechanical modes in a practical power system can be divided into three types: intraplant modes; local modes; and interarea modes. The chapter provides an overview of the development of linear models for nonlinear systems. There are two methods commonly used for generating linearized models: using analytical expressions, and using a numerical perturbation method.