Marginal Power-Based Maximum Power Point Tracking Control of Photovoltaic System Under Partially Shaded Condition

In this article, a two-stage maximum power point tracking algorithm is presented to track the global maximum power point of photovoltaic systems in partially shaded conditions. The proposed tracker uses an intelligent sampling procedure based on a fractional open-circuit voltage method and takes initial samples from the power-voltage characteristic of the photovoltaic array. Then, it determines the marginal array power around each sample. Using these marginal powers, the samples that definitely are not in the vicinity of global maximum power point are eliminated, and neighborhood of these samples are not searched in the global search stage. As a result, the search area gets smaller and global maximum power point is found accurately and rapidly. Furthermore, an algorithm is suggested to estimate module voltage at its maximum power point, which is used in the proposed maximum power point tracker. Eventually, several simulations are carried out through MATLAB/Simulink in order to evaluate the performance of the new tracking method and compare it with recently presented methods. Experimental results are also presented to verify the validity of the developed tracker.