  This paper presents an algorithm for power curtail-ment of photovoltaic (PV)
systems under fast solar irradiance intermittency. Based on the Perturb and
Observe (P&O) technique, the method contains an adaptive gain that is
compensated in real-time to account for moments of lower power availability. In
addition, an accumulator is added to the calculation of the step size to reduce
the overshoot caused by large irradiance swings. A testbed of a three-phase
single-stage, 500 kVA PV system is developed on the OPAL-RT eMEGAsim real-time
simulator. Field irradiance data and a regulation signal from PJM (RTO) are
used to compare the performance of the proposed method with other techniques
found in the literature. Results indicate an operation with smaller overshoot,
less dc-link voltage oscillations, and improved power reference tracking
capability.
