DC Bus Voltage Stabilization and SOC Management Using Optimal Tuning of Controllers for Supercapacitor Based PV Hybrid Energy Storage System

Abstract

The global initiative of decarbonization has led to the popularity of renewable energy sources, especially solar photovoltaic (PV) cells and energy storage systems. However, standalone battery-based energy storage systems are inefficient in terms of the shelf and cycle life, reliability, and overall performance, especially in instantaneous variations in solar irradiance and load. In order to overcome this, a combination of a supercapacitor and battery-based hybrid energy storage system (HESS) is considered as an emerging and viable solution. The present work proposes an optimally tuned tilt-integral (TI) controller to develop an efficient power management strategy (PMS) to enhance the overall system performance. The controller parameters are tuned by optimization of the time-domain design specifications using a gradient-free simplex search technique. The robustness of the proposed TI controller is demonstrated in comparison to PI and fractional-order PI (FOPI) controllers. Furthermore, extensive experimentation was carried out to analyze the effectiveness of the proposed approach for DC bus voltage stabilization and state-of-charge (SOC) management under varying operating conditions such as solar irradiance, load, temperature, and SOC consumption by battery.

Keywords

• photovoltaic
• batteries
• supercapacitor
• SOC consumption
• DC bus voltage stabilization
• PI controller