Novel robust adaptive controller based on non-quadratic Lyapunov functions for FACTS

Abstract

Most of power control engineers and researchers who work in the area of FACTS design and control face many hurdles such as the inaccurate estimation of system parameters and ensuring an optimal stable performance in the presence of disturbances; such hurdles can not be problems any more with the aid of these new robust adaptive control loops, presented in this paper. An optimal performance can still be maintained even while using inaccurate system data, by applying new model reference adaptive control (MRAC) schemes developed by the authors. This paper presents a novel robust adaptive controller for FACTS that is able to tackle the arising uncertainty in system parameters, internal and external disturbances in power systems, while maintaining system dynamic stability which is considered as the main contribution of this work. The proposed controller employs either standard Quadratic or new non-quadratic Lyapunov functions (NQLF) that act to drive the output error signal (e1), defined as the error in the load terminal voltage, rapidly to zero. A SVC dynamic FACTS model, developed by the first author et al., is implemented in this application. Simulation results, obtained using MATLAB/SIMULINK, compare the output error signal while using fixed controller parameters with the use of robust adaptive control loops based on either quadratic Lyapunov function (QLF) or new NQLF. Obtained results confirm the capability of the suggested control technique, specially the controller based on NQLF, in restoring system dynamic stability as well as improving system performance in presence of disturbances which has not appeared in literature yet.