Analysis of the End Electric Field of 66 kV Dry Transformer in Offshore Wind Power

With the continuous increase in the capacity and scale of offshore wind power units, 66 kV has more technological and economic advantages compared to 35 kV AC power collection schemes. However, the end electric field of high voltage level dry transformers faces more severe tests. Therefore, this article constructs a 1/2 cross-section geometric model of the transformer, which considers the structure of iron yokes and pads that have a significant impact on the end electric field. The distribution characteristics of the electric field at the end of the dry-type transformer were calculated and obtained through finite element analysis. The locations with higher field strength are concentrated in the insulation of the high-voltage winding end. The surface electric field strength at the contact position between the coil and the pad and the internal electric field strength of the coil can reach 2.63 kV/cm and 6.85 kV/cm, respectively. Finally, the structure of the high-voltage coil pad under the optimal electric field was analyzed, and the research results have important guiding significance for the development of 66 kV dry-type transformers.