An Opportunity Cost Based Replacement Strategy for Transformers

Accurately evaluating the economic life of a transformer not only plays an important role in appropriately scheduling its secure and economic operation, but also provides the basis for determining its replacement strategy. Considering the characteristics of the transformer failure rate in its life cycle, the Arrhenius-Weibull model which is widely employed for describing the transformer temperature aging failure is first presented to model the loss failure stage in the failure rate bathtub curve. A transformer age reduction factor is next introduced to characterize the effect of transformer maintenance. Then, the opportunity costs are calculated through comprehensively considering the economic factors of the transformer maintenance and replacement. Finally, the opportunity costs of the transformer maintenance and replacement are used as the criteria for determining the optimal replacement timing of the concerned transformer. A sample example is served for demonstrating the essential features of the presented method.