Evaluation of Sustained and Momentary Interruption Impacts in Reliability-Based Distribution System Design

The reliability and power-quality (PQ) expectations of the power distribution system are steadily increasing. Performance-based rates and/or incentives are being put into place in order to ensure that reliability standards are being met. The distribution system planners, designers, and operators are given the task of developing system upgrades that will successfully meet these new performance goals. This is not always an easy or straightforward task, particularly in cases where a system upgrade can impact the various reliability and PQ indices in different directions. This paper develops an incremental cost-based approach to providing linkage between the sustained and momentary interruption indices. This new approach is readily implementable, and also readily adjusted to meet local performance goals. This paper also presents a case study involving a distribution feeder, and assesses the use of the method in evaluating fuse saving/fuse melting and sectionalizing switch automation upgrades on the line.