Enhanced energy storage utilization under partial shading conditions in a microgrid with flexible photovoltaic power control

Abstract

Flexible power point tracking (FPPT)-based photovoltaic (PV) controls are widely applied to mitigate PV power fluctuations due to intermittent irradiance changes. In dc microgrid (dcMG) systems, the utilization of a battery energy storage system (BESS) can be alleviated by adjusting the PV power generation to meet the demand. However, conventional FPPT algorithms implemented in dcMG controls may become ineffective under partial shading conditions (PSCs), as the PV operation can be trapped at local maximum power points. Consequently, the BESS is utilized to compensate for the power mismatch between the PV generation and demand, even when the demanding power is below the global maximum power point (GMPP). To address this issue, a scanning-aided control technique for dcMGs with PV and the BESS, along with a simple PSC-resilient FPPT algorithm, is proposed. The proposed control technique routinely scans the power-voltage curve of the PV array to identify the GMPP. The obtained GMPP information is then fed to the proposed PSC-resilient FPPT algorithm, which dynamically adjusts the PV generation for the dc-link voltage regulation. The BESS with the proposed method only intervenes when the load demand exceeds the GMPP or when it needs to restore its state-of-charge, thereby, enhancing its usage. The efficacy of the proposed dcMG control technique and the PSC-resilient FPPT algorithm are investigated through simulations in MATLAB/Simulink.