A Simple Adaptive Enhancer of Voltage Stability for Generator Excitation Control

This paper presents a simple adaptive devise for robust stability of power systems in the presence of time-varying parameters. Power systems are complex control systems with uncertain and time-varying parameters. For a first introduction of the idea we use a simplified generator excitation control system. Due to uncertain time-varying loads and parameters, fixed controllers may result in poor behavior or even total divergence. This paper is motivated by the properties of a particular simplified adaptive control procedure (SAC) to maintain the desired performance over large ranges of realistic operational and environmental conditions, and guarantee global stability of the nonlinear adaptive control system. The safety device measures the difference between the desired reference voltage and the actual voltage and interferes only if this difference is remarkable. This way, the power system is almost unaffected during regular times and strongly supported during difficult times. Simulation of difficult situations illustrate the power of the nonlinear adaptive device.