The Impact of Wind Farm Flicker on Transformer Gassing

Wind turbines make use of a step-up transformer to feed into the local wind farm network. These are often oil-filled transformers that require regular evaluation of dissolved gas concentrations as an early warning of internal faults, and heating that accelerates insulation break-down. This paper analyses the unexplained dissolved hydrogen and show specific line resistance values can be associated. Comparison of field data at affected and unaffected locations shows a significant difference in flicker. Using first principles in network principles, a model was derived that predicted similar frequency spectra and flicker values when compared to field measurements. Instantaneous changes in wind speed cause similar changes in generated power and were found to correlate well. This model helps to identify the range of conditions that cause an increase in unexplained gassing. This risk of hydrogen production at wind farms is now better understood. Possible changes in design parameters to mitigate this concern on transformer susceptibility to flicker can be derived.