Aging of distribution transformers due to voltage harmonics

This paper presents an evaluation of the possible effects of increasing the harmonic voltage distortion limits on the lifetime of distribution transformers. This analysis is done through the combination of the current and voltage harmonic distortions to determine the effect on the transformer temperature rise and his impact on transformer aging. The effects of current harmonics on transformer load losses and aging have been widely studied. In contrast, the effects of voltage harmonics remain still scarcely investigated, very few documents analyze this disturbance related to transformer aging and quite rarely it has been included in the transformer aging models operating under non-sinusoidal conditions. Both harmonic distortion effects will be compared through the transformer thermal-electrical model to characterize the transformer loss of life for different levels of voltage and current distortion.