A Distributed Adaptive Super-Twisting Sliding Mode Controller for Voltage and Frequency Restoration in Islanded Microgrid

This article presents design of an adaptive super-twisting sliding mode control (ASTSMC) scheme for an islanded ac microgrid (MG). The objective of this control design is to effectively restore the voltage and frequency distortion at the point of common coupling (PCC) during intermittent variation in solar irradiation and unbalanced loading. The adaptive gains of the controller are updated by employing a self-tuning approach to handle system uncertainties, and the sliding mode controller (SMC) compensates for the deviation caused by the primary layer. Lyapunov theory is explored to verify the stability and robustness of the proposed controller. The ASTSMC considers information from the neighboring MG. The proposed controller is implemented first in MATLAB/Simulink, followed by real-time experimentation using a prototype MG system interfaced with a microlab box. The performance of the proposed controller is compared with that of a nonadaptive-based distributed averaging (NADA) controller. From the obtained results, it is observed that the ASTSMC outperforms the NADA controller during both transient and steady-state conditions. Further, the proposed ASTSMC scheme provides fast convergence of the state variables to their nominal values in face of uncertainties in the MG system.