The Effect of Bubble Movement on the Streaming Discharge of Transformer Oil

The discharge effect caused by microbubbles generated due to local overheating during long-term operation of transformers can further reduce insulating properties. Therefore, this paper systematically investigates the impact of microbubbles on discharge in transformer oil. First, a two-phase flow simulation model of bubbles in oil was established; Then, the effect of bubble position on the initiation and development of discharge in transformer oil was explored; Finally, patterns of the effect of bubbles in oil on temperature and space charge density during discharge were analyzed. The research results indicate that bubbles in oil always move towards areas with a weaker electric field. The weaker electric field strength inside the bubbles shortens the discharge initiation time by approximately 50% and concentrates the discharge channels. In addition, bubbles significantly increase the maximum temperature and space charge density of the discharge channels. The research has significant engineering implications for the long-term stable operation of transformers.