The impact of DC/AC ratio on short-term variability of utility-scale PV plants

The growing concern of frequency regulation resulting from high penetration of large-scale Photovoltaic (PV) power plant leads to the need of understanding the characteristics of short-term PV variability and mitigation approach. This study takes the advantage of the trending PV design which is an oversized DC capacity to the AC capacity of the PV plant to study the impact of this oversizing on the short-term variability of PV output. The term, DC/AC ratio is used to define the ratio of the DC capacity to the AC capacity of the plant. Some countering effects are found between the increasing magnitude of variability due to DC capacity expansion and the limit of the AC capacity. Overall, the variability is bounded by increasing the ratio while the impact is more significant during the peak generation period.