Disturbance observer-based higher-order sliding mode controller for frequency regulation of hybrid power systems

Abstract

This paper discusses a higher-order integral sliding mode controller (HOISMC) for frequency regulation of an isolated and interconnected hybrid power system. An improved slap swarm algorithm (ISSA) has been adopted and implemented for concurrent tuning of the HOISMC's parameter to alleviate system oscillations and improve system stability in the wake of uncertain perturbations. To enhance control performance and minimise the chattering problem of sliding mode controller, a disturbance observer is designed and incorporated to refine HOISMC's control law. Simulation outcomes of the ISSA have been evaluated and compare with existing optimisation technique and the results reported in the state-of-art. The comparative study confirms the superiority of DO-HOISMC over the others controllers in terms of damping system oscillations. Moreover, the mastery of the DO-HOISMC is assessed incorporating system nonlinearities and control input-delay. Finally, the closed-loop robust stability of the studied HPS has been affirmed by applying Kharitonov's theorem considering parametric uncertainties.