Implementation of a modified circuit reconfiguration strategy in high concentration photovoltaic modules under partial shading conditions

Abstract

A modified circuit reconfiguration (MCR) technique for high concentration photovoltaic (HCPV) modules under partial shading conditions (PSCs) is proposed. Although HCPV modules have high conversion efficiency, they are sensitive to changing environments, especially PSCs. In response, the MCR strategy exploits the reconfigurable wiring of HCPV modules to implement the dynamic circuit reconfiguration (DCR) technique. In doing so, the hardware switches and complex control algorithms of the conventional DCR are simplified to reduce cost. Moreover, an irradiation estimation method is proposed for string current equalization using existing switches and connections. Two circuit-model prototypes, one square and one rectangular, were simulated to evaluate the proposed MCR strategy. Evaluation results demonstrate that the average output-power and conversion-efficiency improvements of the square and rectangular modules were around 31.07% and 5.00%, and 32.79% and 5.23%, respectively, when compared with the original Series connection topology. In addition, after reconfiguration by MCR, the module’s GMPP power was improved and the number of LMPPs reduced, which simplified the P-V curves. Furthermore, reliability tests demonstrated that with a small reconfiguration processing time ratio (0.06–0.28%), the daily energy harvested from the rectangular module was improved around 15%. The proposed MCR strategy has the advantages of reducing the hardware/software costs and lowering circuit losses. Additionally, the MCR method can increase the output power and efficiency of an HCPV module with high dispersion ability. The proposed method and prototypes can also be extended to larger scale arrays or implemented with other PV systems.