3　Proposal of a method for determining the direction of cloud flow in one and two directions from all-sky images

Abstract

We have been evaluating the optical flow from all-sky images to determine the direction of cloud flow in order to predict solar power generation. However, the methods we have used in our development to date have sometimes failed to find the correct direction. In addition, when the cloud flow was assumed to be in one or two directions, it was possible to determine the direction, but not to determine whether the cloud flow was in one or two directions. Therefore, this study attempted to select a more appropriate optical flow method and develop a method to determine the number of cloud flow directions using the circular standard deviation.