Probabilistic cost-benefit analysis-based spare transformer strategy incorporating condition monitoring information

Abstract

Determining an economical and reliable spare transformer strategy is an essential and challenging task for power utility companies. This study proposes a probabilistic cost-benefit analysis-based spare transformer strategy incorporating condition monitoring information. Not only the actual wearing condition of each transformer, but also the impacts of a transformer ageing process on spare transformer strategy are considered by the proposed method. First, the actual wearing condition and functional age of each transformer are estimated based on condition monitoring information. Secondly, the ageing process and ageing failure rate of each transformer are modelled by combining a Weibull distribution and its functional age. Thirdly, based on probabilistic cost-benefit analysis, the outage costs, as well as economic benefits under different inventory sizes, are estimated. The transformer's ageing process is modelled and considered in the determination of the optimal number and the acquisition timing of spare transformers. Finally, a transformer substation group and its condition monitoring information, and the real spare transformer strategy collected from a regional power grid in China were used to demonstrate an application of the proposed method. The results indicate that the spare transformer strategy determined by the proposed method not only enables the power utilities to avoid economic losses but also guarantees a high cost-benefit ratio of spare transformer strategy.