Numerical simulation of the effect of ion migration rate and electron drift mobility fluctuations during phase transition on the propagation of streamer in natural ester

The mechanism of ion migration rate fluctuation characteristics on the formation and propagation of streamer discharge in insulating oil still remain unclear, a multi branches streamer discharge model for natural esters is established in this investigation. The propagation mechanism of streamer structure under positive and negative voltages at the microscale is revealed. The influence of electronic drift and ion migration rate fluctuations on the branching and propagation characteristics of streamer is obtained through finite element analysis. The results indicate that the simulated streamer morphology is consistent with the experimental results. The electric field strength at the streamer head remained at its maximum and exceeded 1×10⁷ V/m. In addition, the propagation time of negative streamer discharge is earlier than that of positive streamer discharge, and the electron drift speed in negative streamer is much higher than that in positive streamer. Furthermore, the electron drift speed in the positive streamer head is relatively fast, while the electron drift speed in the negative streamer channel is fast, resulting in a wider negative streamer channel than the positive streamer channel. Therefore, we believe that the electron drift speed of electrons is an important reason for the difference in positive and negative streamer morphology. This study provides both the new insights into the improvement of streamer discharge models and reference for the formation mechanism of streamer discharge in insulating oil.