LVRT capability based on P‐V curve fitting under partial shading conditions

Abstract

The new generation of photovoltaic (PV) systems represents higher sustainability during grid faults thanks to increased ancillary services, such as low voltage ride-through (LVRT) capability used when the PV system is subjected to voltage sag. Unlike previously presented strategies that just dealt with voltage sag problem under uniform radiation conditions, in this study, a new control strategy implementing LVRT capability during low-voltage faults under partial shading conditions is proposed. First, radiation levels are estimated by using the least-squares curve fitting (LSCF) algorithm. Second, the voltage/current of maximum power points (MPPs) and minimum power points are calculated. Also, the corresponding algebraic function for the (Power - Voltage) P-V curve is extracted using only PV voltage and power vectors. Finally, under partial shading conditions, the moving operating point to the right side of MPP is well-achieved through a power proportional-integral controller. To validate the effectiveness of the proposed control strategy, simulations and experiments are conducted on PV systems. The simulation and experimental results and the comparison made between this algorithm's performance and other methods confirm that the proposed algorithm outperforms other methods in terms of high accuracy, fast dynamic and low oscillations in different partial shading conditions and with different radiations.