Design of frequency conversion short circuit heating drying prototype for ultra-high voltage transformer

Abstract This paper focuses on the problems of low drying efficiency of hot oil drying method and high proportion of reactive power in transformer heating caused by only using power frequency short-circuit heating power supply when Ultra-High Voltage (UHV) transformers are installed in areas with large temperature difference between day and night in northwest China. A prototype of frequency conversion short-circuit heating and drying device suitable for electrical parameters of UHV power transformers is designed and developed to further improve the heating efficiency of transformers and meet the drying needs of transformers. In this paper, the overall design scheme and design rules of the frequency conversion short circuit heating and drying prototype are described in detail. The components and functions of the prototype are introduced, including the thyristor cooling system, the protection equipment to ensure the safety of personnel and equipment, and the new man-machine operating system to enhance the intelligent level of the equipment. Finally, the on-site heating conditions and some operation steps are introduced, and the output test of the frequency conversion short-circuit heating prototype is completed. The experiment shows that the output waveform is stable when the voltage frequency is as low as 0.01 Hz, which meets the expected goal.