Cumulus Cloud Shadow Model for Analysis of Power Systems With Photovoltaics

Distributed photovoltaic (PV) power generation systems are being rapidly deployed worldwide, causing technical problems such as reverse power flows and voltage rises in distribution feeders, and real and reactive power transients that affect the operation of the bulk transmission system. To fully understand and address these problems, extensive computer simulation studies are required. To this end, this paper sets forth a cloud shadow model that can be used to recreate the power generation of rooftop PV systems embedded in a distribution feeder, or that of a utility-scale PV power plant, during days with cumulus clouds. Realistically shaped cumulus cloud shadows are modeled as fractals. The variation of the irradiance incident on each PV system in an area of interest is then obtained by considering the movement of the cloud shadow over the area. The synthesized irradiance has satisfactory temporal and spatial characteristics. The proposed model is suitable for Monte Carlo simulations of power systems with high PV penetration.