Higher Order Barrier Function based Robust Non-linear Control of DC Microgrid

Abstract

Direct Current (DC) microgrids are getting popular due to their capability to incorporate renewable energy resources. An efficient control scheme is still required to ensure the energy management in hybrid energy storage system (HESS) of DC microgrid (MG) in the presence of time-varying disturbance of unknown upper bound. In this work a novel nonlinear barrier based adaptive super-twisting sliding mode controller (BAST-SMC) is designed for DC microgrid which involves fuel cell (FC), battery, ultra-capacitor (UC) and PV system as its power sources. Firstly, the mathematically model for DC microgrid is derived then the proposed controller is designed for regulating the DC output voltage of the grid while the respective reference currents of power sources are tracked in the presence of time-varying disturbance of unknown upper bound and its derivative. The proposed controller starts to cater for the disturbance from the initial time and it removes the problem of overestimation of adaptive gains. Moreover, the controller brings the output voltage to the desired voltage within the predefined neighborhood of desired DC bus voltage. The Lyapunov stability technique is used to prove the hybrid microgrid’s asymptotic stability. The proposed controller’s performance is evaluated by simulating it on MATLAB/Simulink, and the results are compared with sliding mode control (SMC). The proposed controller shows better dynamic performance and robustness against time-varying disturbance of unknown upper bound as compared to other controllers. Index Terms—DC Microgrid, Hybrid energy storage system, Barrier based Adaptive Super-twisting Sliding mode controller (BAST-SMC), Barrier Function, Sliding mode control, Fuel cell, PV Panels