Atmospheric Intelligence for Hybrid Power Advancements: Volume 3 (Whole Sky Image Percent Cloud and Blue Sky Analyses)

Author(s):

Gail Vaucher, Jarrod LaRosa, Michael Lee, and Robert Jane

Abstract:

This report documents a blue sky algorithm milestone used in the process of converting whole sky imagery into informative quantities needed to calculate surface layer irradiance. Power resource diversity is critical in maintaining future reliable and consistent electrical flow. Forecasting power generation is key in managing and optimizing multiple resources. Photovoltaic (PV) technology is an energy source that is ready for this hybridized power strategy. PV power is a function of irradiance. Primary irradiance inhibitors are atmospheric clouds. A Whole Sky Imager (WSI) visually captures clouds and can quantify power production impacts. Earlier research defined sky type using a red–green–blue thresholding method. Nonlinear correlations led to a hue–saturation–value method that highlights blue sky pixels. This approach was applied to ground objects and led us to determine that image artifacts represent <3% of the total pixel count. Comparing calculated cloud cover to sky observer values, overcast cases showed good agreement. Clear cases were within a 3% difference, reinforcing artifact challenges. Partly cloudy cases produced favorable results. All WSI image elements were tallied and cross-checked against the WSI pixel total. Results were well within acceptable levels. This research improved WSI analysis capabilities, producing algorithms poised for applications that will ultimately reduce Warfighter vulnerabilities/delayed disaster relief recoveries.