A novel approach for maximum power point tracking of a PV generator with partial shading

Abstract

This paper presents a novel two-stage approach for tracking the maximum power point (MPP) of a large photovoltaic (PV) generator under non-uniform irradiance. The non-uniform irradiance in large PV arrays is attributed to partially shaded PV modules and may significantly increase the complexity of the MPP tracking problem. In Stage 1, the method makes use of real-time irradiance measurements in certain regions of the generator to estimate the power versus voltage (P-V) curve and to deduce an estimate of the global peak region. This is followed in Stage 2 by a single peak tracking approach starting at the estimated global peak, which combines ripple correlation and incremental conductance, to accurately locate the exact global power point. The system consists of a PV generator, with pyranometers distributed across it, a DC-DC converter feeding a battery, and a controller implementing the tracking algorithm. The system simulation model was developed in MATLAB, taking into consideration the implementation of bypass and blocked diodes together with the pyranometer irradiance inputs. The paper first presents a modeling and simulation scheme suitable for studying the I-V and P-V characteristic curves of a PV array with partial shading configuration given the exact irradiance values. This is followed by a method of global peak region estimation knowing the location and readings of the distributed pyranometers. Tracking results of the two-staged approach are demonstrated under various shading configuration cases.