Study on Improvement of MPPT Efficiency in PV Generation System with Partial Shadow

The maximum power point of PV （photovoltaic） generation moves depending on weather conditions and load. Therefore, it is significant to make sure that the panels can work at the maximum power point under MPPT （maximum power point tracking） control. However, it has the problems of low efficiency and unstable operation when panels are covered by the partial shadow. The result is that the output power may be substantially decreased. To overcome this issue, the authors propose a new plug-in operation point correction system. This system is put between PV panels and PCS （power conditioning system） in the existing PV generation system. In this paper, the experimental results describe that the output electric energy increases approximately 1.4 times as compared with the conventional system when the proposed correction system is inserted.

Research on Maximum Power Point Tracking in Redundant Load Mode for Photovoltaic System

In order to ensure that the photovoltaic(PV) array always works at the global maximum point of power to increase the system's overall efficiency, this paper leads the study on maximum power point tracking(MPPT) in redundant load mode. A new control system is designed by combining the redundant electronic load module, embedded controller, supportive capacitor and boost circuit. The system adjusts duty ratio of boost circuit dynamically based on the maximum power point parameter provided by redundant load unit in order to realize MPPT. An experiment shows that no matter whether system is under an even illumination or partly perturbed by shadow, this method can find the exact maximum power point.

PV Array Reconfiguration Based on the Shaded Cells'Number for PV Modules

Reconfiguration can increase the output power for a PV array under partial shadows.However,traditional reconfiguration methods consider the PV module as either totally shaded or totally unshaded,and module-based simulation is employed to evaluate the reconfiguration effect.Actually,there is an unneglectable error when treating a partially shaded PV module as totally shaded,through using a more accurate cellbased simulation.Based on the analysis of the determinant factors on MPPs’power of a PV array,a new reconfiguration method is proposed based on the exact partial shadow shape projected on the PV array.This method restructures the electrical connection among PV modules of a PV array according to the shaded cells’number(SCN)of every PV module.Extensive cell-based simulations are carried out on a PV array to verify the effectiveness of the proposed SCN-based reconfiguration method.Comprehensive comparisons among various reconfiguration methods and shadow distributions clearly show its suitability to different irregular shadows and its superiority in PV output power enhancement.