Evaluation of reliability indices and outage costs in distribution systems

Reliability evaluation of distribution systems assesses the adequacy of the load points in regard to providing a suitable supply to customers. This area has received increased interest during the past few years. A considerable number of papers have been published describing the development and application of the available techniques for modelling the various features of a distribution system and for evaluating the reliability indices. Also a few publications have considered the evaluation of probability distributions of the reliability indices for radial systems. However, due to the complexity of the analysis and the need to consider overlapping outages in meshed networks, these techniques are not able to evaluate the probability distributions for such networks. Also, further considerations are still required in the evaluation of interruption costs/reliability worth in order to obtain true and more realistic values that reflect the behaviour of the system under study. This paper describes models and techniques for evaluating the probability distributions associated with the reliability indices in meshed networks. It also presents a procedure for combining costs of interruptions with the probability distributions of interruption durations and of CAIDI to assess the cost of interruptions in meshed networks. The proposed approaches are based on a combination of analytical techniques and Monte Carlo simulation. Finally the paper reports on the results obtained from sensitivity studies developed for bus 1 of the IEEE Reliability Test System