Study on upgrade and renewal of transformers using safety-first model of the optimal portfolio selection

In a response to economic growth, electric power utilities installed many electric power facilities to meet power demand. However, these facilities have aged and should be replaced in the near future. Moreover, the demand is said to constantly increase. Therefore, it is necessary to partially upgrade facilities. In this paper, we upgrade transformers with one of the financial engineering techniques. We also propose the method of upgrading transformers for improving reliabilities and economics.