Research on Electric Field Distribution at Winding End of Converter Transformer Considering Temperature Gradient

Converter transformer is one of the most important equipment in DC transmission system. Its structural design is more complex than the general power transformer, and the problems of electrical insulation and local overheating are more prominent. The temperature rise will change the material properties and affect the performance of insulation. In this paper, a complete multi-physical field coupling simulation model is established, and the electric field distribution characteristics of insulation system affected by temperature gradient are analyzed. The results show that the temperature of converter transformer changes greatly, the maximum temperature rise is 62.55K, and the temperature of winding end is higher, so the coupling problem cannot be ignored. Considering the temperature gradient, the change speed of oil paper insulation field strength is accelerated, which should be paid attention to in the design of converter transformer insulation structure.