Hasan Alizadeh Shiraeh - University of Science and Technology of Mazandaran, Bahshahr, Iran
Kazem Hoseini - University of Azad Sari, sari, Iran
Iraj Ahmadi - University of Science and Technology of Mazandaran, Bahshahr, Iran
Mohamad Mirzaie - Babol Noshirvani University of Technology, Babol, Iran

Transformer is one of the most important components of power system where determining its reliability, available capacity and aging is very important. Due to increasing non-linear loads and adverse effects of harmonics on transformers, studying the reliability of transformers in harmonic load conditions is essential. In this paper, impacts of harmonics on reliability of distribution transformers including available capacity and aging is modeled. The suggested model has been developed in MATLAB programing environment. The load data of three transformers of Mazandaran regional electric company, each one feeding a pure industrial, commercial and residential load, are measured and implemented to the developed software. Using these data, derating of transformer capacity in terms of total harmonic distortion (THD) and impacts of rise of hot spot temperature resulting load harmonics on transformer dielectric and its aging is studied. Simulation results indicate that different amounts of THD resulting different capacity derating and aging acceleration factors.

Aging, Available Capacity, Distribution Transformers, Reliability