USING EXTREMUM SEEKING Brunton-PVSC09.pdf (application/pdf Object)
A novel extremum seeking algorithm that utilizes the inverter
ripple was tested on a simulated array-inverter system using
MATLAB R
/Simulink. This method was benchmarked against
the popular perturb and observe method using 25 minutes
of rapidly varying irradiance data taken in June, 2007 on the
Princeton University solar deck. The irradiance data chosen
represents a worst-case scenario for maximum power point
tracking due to the presence of fast moving, scattered cloud
cover. It was shown that extremum seeking slightly outperforms
perturb and observe in total power efficiency, and drastically
outperforms in transient rise-time to the maximum power point,
with two orders of magnitude speed-up. Additionally, extremum
seeking has guaranteed convergence and stability properties
which are ideal for variable weather conditions and unmodeled
dynamics.
It remains to test the algorithms on the actual solar array
at Princeton University. Additionally, it would be interesting
to compare the algorithms on competing photovoltaic technologies,
namely GE poly-crystalline silicon panels and EPV’s
amorphous silicon thin films, to see how the shape of the panel
IV curve affects tracking performance. Here, only irradiance
variations were considered, although temperature and partial
shading experiments would also be interesting. Finally, a next
step is to extend the extremum seeking algorithm to have a
variable gain and compare with a modified perturb and observe
algorithm with variable increment.
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