Suppressing solar PV output fluctuations by designing an efficient hybrid energy storage system controller

The stochastic nature of solar photovoltaics (PV), marked by high-frequency voltage fluctuations due to dynamic climatic conditions such as cloud cover and temperature variations, presents a significant challenge to power quality stability, especially in microgrids. This variability poses a threat to the stability of power electronic devices responsible for power control and monitoring, potentially compromising the power grid's stability. To address this challenge, energy storage systems (ESS) are commonly employed. In this study, we develop a hybrid energy storage system (HESS) incorporating a battery, supercapacitor, and fuel cell. The primary aim is to adjust the inverter voltage for the photovoltaic system using newly developed proportional-integral (PI) and model predictive control (MPC) controllers within the HESS framework. Importantly, this controller eliminates the need for precise knowledge of system parameters and offers robustness, insensitivity to parameter changes, and resilience to time-varying external disturbances, ensuring satisfactory performance. By mitigating power fluctuations, the generated power can be seamlessly integrated into the grid, significantly reducing costs associated with device damage in the power path.

Notably, we integrate the proposed photovoltaic system with an RLC series load using an IGBT inverter. To assess the performance of the HESS in the proposed photovoltaic system, four distinct scenarios are examined. These scenarios involve altering the PV system's location and testing two energy storage systems, namely the battery and fuel cell, which are separately designed components of the HESS for a 14-bus microgrid.