Optimal Augmentation of Distribution Networks for Improved Reliability

Abstract

Reliability is a crucial factor influencing electricity network planning and has gained considerable attention in the past decade due to the increasing number of weather-related outage events. This article explores connections between network topology and reliability, and proposes a graph-based approach to enhance the reliability of distribution systems by installing new tie-lines. The problem is cast here as an edge-connectivity augmentation problem, with 2-edge connectivity being desired to ensure service restoration under the outage of any single line in the network. However, in practice, such a target may not be economical or feasible. Therefore, a systematic optimization framework is presented in this article to model partial augmentations to the system for improving the reliability at a select subset of nodes. This approach allows for selectively strengthening parts of the network based on connectivity requirements. The article also proposes the use of graph-based metrics to characterize the reliability of distribution networks. Applications of the approach to realistic distribution test systems demonstrate its effectiveness in identifying line additions that can favorably impact system reliability. Numerical results also quantify the reliability improvement achievable through partial augmentation.