A two stage successive estimation based maximum power point tracking technique for photovoltaic modules

摘要

A new method of tracking the maximum power point (MPP) of a photovoltaic (PV) module exploiting the effects of the inherent characteristic resistances of the photovoltaic cells is proposed in this paper. An analysis of the mathematical model of the Ⅳ characteristic of the PV module revealed a possibility of estimating the MPP from its characteristic parameters such as the open circuit voltage (V_(oc)), short circuit current (I_(sc)), series resistance (R_(sc)) and the shunt resistance (R_(sh)). The first stage of estimation process, for obtaining the voltage at the MPP, was facilitated by the effects of the series and shunt resistance on the Ⅳ characteristic of the PV module and the second stage of estimation process was facilitated by the combined process of the first stage of estimation and the condition for extracting the maximum power from the mathematical model of the pv characteristic of the PV module. The estimated voltage at the MPP in the second stage of estimation was found very close to the true MPP. The effectiveness of tracking the MPP with the proposed method has closely matched with the true MPP. This was validated by the results obtained through simulations and experiments. An analysis of the effects of degradation on the performance of the proposed technique showed that the performance was excellent during the first few years and with the update of characteristic resistances in the proposed algorithm the performance was found to be almost invariant. The successful experimental results obtained with a 100 W_p PV module indicate that the technique can be favourably implemented for standalone PV power systems.