Global Extremum Seeking Control of the power generated by a Photovoltaic Array under Partially Shaded Conditions

• Global Maximum Power Point Tracking algorithm is efficient and simple to implement.
• The tracking speed of maximum 23 periods of dither.
• The tracking accuracy of minimum 99.95%.
• 100% hit count for a searching resolution of 0.25%.
• 99.97% tracking efficiency.

This paper analyses the performance of new Extremum Seeking Control scheme which has two adaptive control loops: (1) the searching loop locates the Global Maximum Power Point by sweeping the Photovoltaic pattern based on an asymptotic dither; (2) the tracking loop finds and tracks accurately the Global Maximum Power Point based on similar loop used in Perturbed-based Extremum Seeking Control schemes proposed in the literature. The advantages of the Asymptotic Perturbed-based Extremum Seeking Control scheme in comparison with other Extremum Seeking Control proposals are evaluated as (1) cost and complexity of implementation, and (2) performance obtained based on four indicators: the searching resolution, tracking accuracy, tracking efficiency, and tracking speed. Four solutions are implemented in MATLAB/Simulink software® to evaluate the most efficient method to obtain the asymptotic dither based on the first harmonic of the output signal from controlled process, the Photovoltaic Array under Partially Shaded Conditions. The chosen variant from the four schemes was further analyzed as performance, robustness to Partially Shaded Conditions, fast changes of the irradiation, and environmental noise. Different patterns for the irradiance profile were used to test this control scheme in tracking of the Global Maximum Power Point generated by different Photovoltaic arrays. Two normalization gains are used to adapt the proposed control scheme to different Photovoltaic arrays. The other two gains (the dither’s gain and the loop’s gain) are designed for best performance in sweeping and tracking of Global Maximum Power Point. The performance obtained is similar or superior to the other algorithms used for tracking the Global Maximum Power Point.

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