Asset management of power transformer: Optimization of operation and maintenance costs

This paper proposes asset management of power transformer in order to diminish operating and maintenance costs. The strategy for the asset management consists of failure statistic analysis, assessment on power transformer condition and importance, and inventory management of power transformer spare part. To determine the critical components and failure causes, the failure statistics of power transformer are analyzed. The failure data is used for estimating lifetime of main power transformer components by Weibull distribution technique. To manage maintenance tasks of power transformer, risk-based maintenance is developed by a combination of condition and importance assessment of each transformer. The condition assessment is performed by analysis of electrical test, insulating oil test and visual inspection. The importance is evaluated from load criticality, impact on system stability, possibility of failure, failure consequence, damage to property, as well as social impact and environmental concern. Subsequently, risk-based maintenance in form of risk matrix is developed for evaluating the risk of each transformer. The transformer with high risk will be focused firstly. To optimize spare parts and minimize inventory cost, inventory management strategies are applied to components of power transformer by using Statistical distribution technique and economic order quantity. Therefore, a suitable time period for reordering and optimum ordering quantity are determined. Besides, computerized web-application program is developed for practical use. Finally, maintenance of power transformer fleet can be effectively managed. The proposed method will be further applied to other high voltage equipments.