Energy, Vol.52, 297-307, 2013
Energy harvesting from the PV Hybrid Power Source
In this paper it is proposed a Maximum Power Point (MPP) tracking technique for the photovoltaic (PV) system based on an advanced Extremum Seeking (aES) control that improves both basic performances of the ES control schemes: guaranteed convergence and proved internal robustness. Beside these features that are necessary in case of unmodeled dynamics, other features such as higher search speed and improved accuracy of the MPP tracking process are demonstrated. Thus, different irradiance sequences are used to test the performances of the MPP tracking process, where each of them could represent a worse scenario than in reality. Analysis in the frequency domain reveals the main relationships between the aES control parameters (the values of closed loop gain and dither amplitude) and the performance indicators (the search speed and tracking accuracy). If the dither amplitude is set to be proportional with the magnitude of the first harmonic of the PV power processed in the ES control loop, then the aES control will exhibit a negligible power ripple after the MPP was caught. Therefore, the proposed aES control outperforms all ES control schemes in overall power efficiency. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords:Photovoltaic panel;Energy harvesting;MPP tracking;Extremum seeking control;Harmonics analysis;Hybrid Power Source