Reliability Impacts of Subtransmission and Radial Configurations on the Distribution System

Abstract

Analysis of customer failure statistics indicates that distribution systems make a significant individual contribution to overall customer supply unavailability. Most of these outages originate in the radially connected segments of the distribution system. The contribution from the subtransmission segments, however, can also be significant for certain systems; therefore, there is a need to conduct quantitative reliability evaluation of the overall distribution system in its entirety, i.e., to be able to assess quantitatively the contributions of failures in the radial and subtransmission segments of the system on the customer supply reliability. This paper pertains to evaluating the reliability impact on customer load points of component outages in distribution systems. The effects of changes in component failure rates, adverse weather-related failures, etc. on the individual customer load point reliabilities are presented. Furthermore, the impact of such outages on the various customer sectors, such as residential, small industrial, and commercial are also determined, presented, and illustrated using a distribution test system.