Maximum power point tracking for photovoltaic optimization using ripple-based extremum seeking control
S. L. Brunton, C. W. Rowley, S. R. Kulkarni, and C. Clarkson
IEEE Transactions on Power Electronics 25(10) : 2531-2540, October 2010.
This work develops a maximum power point tracking (MPPT) algorithm that optimizes solar array performance and is robust to rapidly varying irradiance conditions. In particular, a novel extremum seeking (ES) controller which utilizes the natural inverter ripple is designed and tested on a simulated solar array with a grid-tied inverter. The new algorithm is benchmarked against the perturb and observe (PO) method using high-variance irradiance data gathered on a rooftop array experiment in Princeton, NJ. The extremum seeking controller achieves efficiencies exceeding 99% with transient rise-time to the MPP of less than .1 seconds. It is shown that voltage-control is more stable than current-control and allows for accurate tracking of faster irradiance transients. The limitations of current-control are demonstrated on an example. Finally, the effect of capacitor size on the performance of ripple-based extremum seeking control is investigated.
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