Streamer Propagation in Transformer Oil under Lightning Impulse Voltage: Comparison Between Experiment and Simulation

초록

The rapid advancement of artificial intelligence technologies and the resulting expansion of data centers have significantly increased global power consumption. In this context, the role of power transformers has become more critical, particularly in ensuring long-term operational reliability. Transformer oil, as a key insulating medium, plays a vital role in maintaining insulation integrity. The breakdown of transformer oil is primarily attributed to localized electric field enhancement and the formation and propagation of streamers caused by electron avalanches. This study focuses on analyzing streamer propagation characteristics based on a numerical model incorporating charge generation due to ionization and mobility differences between electrons and positive ions. Streamer propagation modes and velocities were experimentally measured under lightning impulse voltage. A simulation model was developed to reproduce these characteristics by considering charge dynamics in the oil. The model was used to analyze streamer initiation and propagation behavior under both positive and negative polarities. The simulation results clearly showed the formation and initiation point of positive streamer propagation. In addition, by applying the electron saturation velocity condition, the 3rd mode propagation speed was identified, and similar results were observed in the experiment. Under negative polarity, differences in space charge distribution, likely caused by changes in electron drift direction, are considered to contribute to variations in streamer shape and dielectric strength. This research provides insights into charge behavior and streamer dynamics in transformer oil, which can contribute to improved insulation design, downsizing, and material selection for power equipment such as transformers and bushings. © 2013 IEEE.

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