Multi-sampling maximum power point tracker (MS-MPPT) to compensate irradiation and temperature changes

Abstract

This paper presents a method to track the maximum power point in a photovoltaic (PV) panel. The proposed method belong to the perturb and observe (P&O) based methods as the method intensionally introduce disturbances in the PV voltage to induce changes on the PV power. In this way, the slope of the pv-characteristic curve can be detected, which reveals the position of the maximum power point (MPP). The disturbance applied is usually a constant increment with varying direction, which is applied to the previous PV voltage reference (or actual PV voltage) to update the next PV voltage reference. Unfortunately, changes on irradiation and temperature may also cause changes in the PV power, which mix with the changes due to the intentional increment. This combination of effects confuses the detection of the slope of the pv-characteristic curve, which may entail a wrong decision of the next increment direction. Thus, conventional MPPT methods fail to track the MPP as they are not able to distinguish the effect of the intentional increment with respect to the effect due to irradiation and temperature changes. The proposed scheme uses a larger number of samplings and a combination of increments directions before taking a decision on the next direction of the increment. This allows to separate the effects caused by irradiation (or temperature) changes from the effects of the intentional increment. The proposed method can thus provide effective MPP tracking despite of changing conditions on irradiation and temperature. Simulation and experimental results of the proposed scheme are provided and compared to those of the conventional P&O under irradiation changes.