The relationship between intrinsic reliability of utility distribution network design to SAIDI: A statistical quantification

Capital planning of a distribution electric power utility aims to improve the reliability of energy delivery to its customers. It is critical to prioritize capital investments on problematic feeders in a distribution network. SAIDI is one of the most commonly used key performance indicators of a utility. An optimal capital investment strategy should seek to maximize the intrinsic reliability of feeders because it minimizes the future risk of service interruption. In this paper, we propose a quantitative approach to measure intrinsic reliability of feeders in a distribution network. We propose a set of metrics that best quantify the design of feeders. The proposed metrics enable computation of robustness of the feeders in case of an outage event. We then apply a statistical ranking method on these new metrics to quantify the intrinsic reliability of the feeders in a utility power distribution network. We present quantitative evaluations from various perspectives including the probability of high SAIDI, 3rd quartile and mean SAIDI. When applying to the distribution network of a US distribution utility company, our approach gives R2 values in the range of 0.86 to 0.94 using linear regression, which indicates a very strong correlation. Hence, this quantification enables better capital planning and more robust networks.