Optimization of Photovoltaic System Performance Under Shading Conditions Through Hybrid Storage

Photovoltaic (PV) systems are sensitive to the shading effect both in grid-connected and stand-alone modes of operation. Shading can potentially reduce the output power of the PV system and cause an imbalance between electricity production and demand. To overcome this problem, a hybrid storage system is often used to cover the power deficit. In this paper, a DC-coupled PV/battery/supercapacitor (PVBSC) hybrid system is used to meet the power requirement of a primary DC load. The PV panel is connected to the common DC bus through a boost converter controlled by an MPPT algorithm, while the battery and SCs are connected to the same bus through bidirectional DC/DC converters. The primary advantage of the proposed system is to ensure an uninterruptable power supply for the DC load despite climatic variations and shading effects. The second advantage is battery life cycle extension since SCs, characterized by their fast response, act as a buffer against large charge and discharge current amplitudes and rapid PV power fluctuations. The proposed system, with its control and energy management system (EMS), is simulated in the Matlab-Simulink environment for a rapid shading effect of 30 seconds. Simulation results prove the effectiveness of SCs in meeting DC power requirements during transient moments, and hence the battery life is extended. The hybrid system shows stable dynamic behavior in all modes of operation. Based on the obtained results, the proposed system can be considered a good solution for stand-alone and grid-connected PV systems.