Operation of transformers: Impact of harmonic loading on transformer losses

Due to the increasing number of electronic devices with non-sinusoidal power supplies applied in today’s grids, transformers are being subjected to enhanced internal heating. Also, additional heating of transformer coils is caused by current waveform distortions due to non-linear loads, which in turn induce additional harmonic components to the fundamental (power frequency) current. The additional heat production, together with the normal heat from the transformer under load, leads to accelerated insulation degradation and reduction of the transformer lifespan. This paper discusses possible mitigation solutions for harmonics on transformers, ranging from specifcation of the transformer to monitoring and operational measures