Robust sliding mode controller for frequency regulation in a microgrid

Abstract

The distribution of power at minimum frequency deviation is a primary objective in an isolated microgrid due to variation in inertia and uncertainties in distributed generations. Thus, in this study, a centralized robust sliding mode controller is proposed to achieve minimum frequency deviation with optimal power distribution among distributed generations in an isolated microgrid. The microgrid model is developed for small signal analysis purpose using the electric vehicle charging model dynamics, the wind energy model dynamics and the run-of-river hydro model dynamics. The proposed controller parameters are optimized using linear matrix inequality (LMI), and its asymptotic convergence law is verified via Lyapunov’s stability theorem. The effective reduction in frequency deviations, time characteristics and chattering in control signals is achieved using the proposed controller. Furthermore, robustness nature of the proposed controller conforms against random plant outage sequence, random load and wind uncertainty. In addition, the performance of proposed controller is compared with existing state proportional–integral–derivative (PID) controller and traditional sliding mode control (SMC) even in presence of random plant outage sequence, load and wind speed uncertainties. The proposed controller is capable of regulating power share scenario intelligently according to load disturbance, plant uncertainties and also reducing time characteristics, oscillations and chattering phenomena in control effort within a short duration. As a result, the responses of proposed controller are compared with existing controllers in terms of improved closed-loop dynamics and its effectiveness. The performance of the proposed controller is demonstrated using MATLAB© simulations platform.