Well-being indices of a sub-transmission system

Supply reliability of sub-transmission systems is usually quantified in terms of two sets of indices, the individual supply/load point indices (average failure rate, average outage duration and average annual unavailability) and the system performance indices (SAIFI, SAIDI, CAIDI, ASUI, ASAI, etc.). These probabilistic indices are very useful not only for assessing the severity of system failures in future reliability predictions but also in assessing the system's past performance. Many utilities, however, continue to use deterministic methods (rule-of-thumb methods) to assess the reliability of their systems. This paper presents a method designated as system well-being analysis, which in addition to the conventional probabilistic risk index of supply point unavailability, also incorporates the specified deterministic criteria in defining additional system healthy and marginal states. The proposed method is illustrated in this paper by calculating the well-being indices of a small but comprehensive test electric sub-transmission system to show the effects of some pertinent factors and deterministic criteria on the system well-being indices. (C) 2000 Elsevier Science Ltd. All rights reserved.