Global Flexible Power Point Tracking in Photovoltaic Systems Under Partial Shading Conditions

Flexible power point tracking (FPPT) aims to regulate the output power of photovoltaic (PV) systems to a predefined value to enable grid support functionalities, such as virtual-inertia provision. Even though partial shading is a common condition in PV systems, especially in small-scale residential PV systems, the current literature, only investigates FPPT control under uniform shading conditions. This article proposes a novel global FPPT (GFPPT) algorithm to provide two functionalities in PV systems under partial shading conditions: first, constant power control (CPC), in which the PV power is regulated to predefined reference value, and second, power reserve control (PRC), under which a constant power reserve is kept in the PV system under steady state to enable grid support under transients. The conventional global maximum power point tracking (GMPPT) algorithm is also modified to adapt with the proposed GFPPT algorithm. The aim of such modification is to obtain faster dynamics after the detection of any environmental changes. Experimental results under dynamically changing partial shading conditions verify the effectiveness of the proposed algorithm in providing CPC or PRC functionalities in PV systems.