Deriving Transformer Equivalent Age for Power System Reliability Assessment from Asset Condition Score

Abstract

The paper proposes a method to derive an equivalent age from asset condition scores in order to incorporate asset condition into existing reliability assessment techniques. The method is related to end-of-life failure to inform replacement decision-making process. The paper projects the age cumulative distribution function (CDF) of a fleet of power transformers into the cumulative distribution function (CDF) of their condition scores. A relationship between condition score and age was formulated by using curve fitting techniques. Case studies were performed on a generic test system to compare system and load point reliability indices using the chronological age and the derived equivalent age. The results showed that using equivalent age resulted in different critical load points than the ones identified when using chronological age.