交流电压下变压器油中流注发展时空演化的光-电信号特征研究

The streamer discharge is the pre-breakdown phenomenon including inception and propagation process of discharge, which is featured by high degree of ionization, high propagation velocity and random branching characteristics. Studying streamer discharge in transformer oil is of great importance to deep understand the mechanism of liquid dielectrics discharge and improve the quality of oil-paper insulation. The steamer propagation process experimental platform is set up to obtain the current pulses and optical image of streamer. It is found that current pulses of negative streamers include four patterns, i.e. single pulse, increasing pulses, decreasing pulses, and first increasing then decreasing pulses. The negative streamer is in a nearly spherical shape and develops slowly with the rise of applied voltage. The positive streamer current pulses are in the form of pulses burst, where the streamers are in a filament-like shape with a random branching characteristic. The inception and propagation mechanism of streamer is also discussed, and several parameters of streamer including radius and velocity are calculated. The results show that the radius of negative is about 80μm, and the diameter of positive streamer is 60~80μm with 3km/s of the average velocity, which are in accordance with the experimental results. It is concluded that the inception and development mechanisms of positive and negative streamers are different.