Nonlinear Control of a Photovoltaic Pumping System under Partial Shading

This paper proposes a new control technique to Track the Global Maximum Power (GMPT) of a photovoltaic pumping system under partial shading. Indeed, when weather conditions are uniforms, the P-V characteristics of the photovoltaic panel (PV) have a single point of maximum power (MPP). In this case, conventional MPPT techniques can easily track the MPP. However, under non-uniform conditions of irradiation and temperature, the P-V characteristics of PV panel have several local maximum points. At this time, the classical methods of MPPT are unable to pursue the global power point (GPP). The proposed technique is based on the nonlinear methods and on the scanning of P-V curve by a capacitor connected to the output of PV panel. The performance of this technique is evaluated in MATLAB software. The simulation results show its ability and pursuit performance under varied meteorological conditions.