Reliability Assessment of Network Planning Options Used in Distribution Stations

This paper describes a reliability study conducted at Hydro One to compare the reliability of three network planning options normally used in distribution stations. The options include designing each station in the distribution system with redundancy, designing stations so that loads can be transferred between stations and the use of spare unit transformers. In this study, probabilistic methods based on Markov models are developed to assess the reliability of each planning option. In addition, the proposed reliability models are also used to assess the overall distribution system reliability when a combination of planning options is assumed. Examples are provided to illustrate the proposed reliability models and to compare their reliabilities.