Renewable Energy Integration using Supertwisted Integral Backstepping Control of DC Microgrid

Achieving net-zero carbon emissions requires optimized use of renewable energy sources with efficient DC interfaces and control through microgrids. An efficient control system is required to integrate these sources in DC microgrids seamlessly. In this work, we propose a supertwisted integral backstepping (STIBS) based nonlinear controller for efficient and robust control of a DC microgrid involving photovoltaic (PV) generation and battery, ultracapacitor based hybrid energy storage system (HESS). We use the state of charge based rule for energy management and reference generation for HESS, derive the control laws using the system's state space model, and ensure the asymptotic stability of the system through Lyapunov functions. We simulated our proposed controller in MATLAB/Simulink environment and compared its performance with state-of-the-art Lyapunov function, sliding mode, and integral backstepping controllers. Our results show significant improvement in DC bus voltage regulation with a minimal overshoot of 1.05%, minimal undershoot of 1.89%, a fast settling time of 0.008s, and a low steady-state error of 0.025V. These improvements show that the proposed controller surpasses the state-of-the-art nonlinear controllers for fast and robust control of DC microgrids under renewable power intermittence and load-side variations.