Chapter 2
System Modeling and Stability Problems
Electric power systems are nonlinear in nature. Their nonlinear behaviors are difficult to predict due to (1) the extraordinary size of the systems, (2) the nonlinearity in the systems, (3) the dynamic interactions within the systems, and (4) the complexity of component modeling. These complicating factors have forced power system engineers to analyze the complicated behaviors of power systems through the process of modeling, simulation, analysis, and validation.
2.1 INTRODUCTION
The complete power system model for calculating system dynamic response relative to a disturbance comprises a set of first-order differential equations:
describing the internal dynamics of devices such as generators, their associated control systems, certain loads, and other dynamically modeled components. The model is also comprised of a set of algebraic equations,
describing the electrical transmission system (the interconnections between the dynamic devices) and the internal static behaviors of passive devices (such as static loads, shunt capacitors, fixed transformers, and phase shifters). The differential equation (Eq. 2.1) typically describes the dynamics of the speed and angle of generator rotors; the flux behaviors in generators; the response ...
