Optimal Capacity Management of Substation Transformers Over Long-Run

Muhammad Humayun*, Bruno de Oliveira e Sousa, Amir Safdarian, Mubbashir Ali, Merkebu Z. Degefa, Matti Lehtonen, Mahmud Fotuhi-Firuzabad

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)


The management of transformers' capacity is a vital task for planners and asset managers due to their high cost. This paper proposes an optimization model for capacity management of transformers in a substation over long-run. The model considers the present worth costs of investment, losses, maintenance, reliability, and the salvage value of transformers for providing the optimal selection and scheduling of multistage transformer installations and their refurbishments. In the optimization model, growing failure rate of transformers along with their age is incorporated and the cumulative loss-of-life (LOL) of transformers is also used in determining their salvage value. The developed model is applied for planning and management of transformer capacities for a residential load dominant two-transformer primary distribution substation over a period of 40 years. The simulations are performed for various case studies representing the situations encountered by utilities. An extensive sensitivity analysis is also conducted for several conditions of the system parameters. The numerical results indicate the worth of inclusion of variable failure rate and LOL of transformers in their capacity management.

Original languageEnglish
Pages (from-to)632-641
Number of pages10
JournalIEEE Transactions on Power Systems
Issue number1
Publication statusPublished - Jan 2016
MoE publication typeA1 Journal article-refereed


  • Capacity planning
  • loss-of-life
  • primary transformer
  • salvage value
  • substation

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