Simulation on the Evolution Law of Streamer and Characteristic of Discharge Pulse in Transformer Oil at Impulse Voltage
With the development of new power systems,the electrical stress environment of oil-paper insulation becomes more complex,and the discharge behavior of oil-paper insulation under transient voltage has attracted much attention.In order to make up for the insufficiency of insight into the microscopic mechanism through experimental research,a field-circuit coupling model of streamer in transformer oil is constructed based on the total current theory,and the evolu-tion law of streamer at impulse voltage and its influencing factors are studied.The waveform characteristics of discharge pulse and its internal relationship with the streamer evolution are revealed.The results show that the streamer in trans-former oil at transient pulse can be divided into three stages,namely,spherical development,directional development,and streamer dissipation.The field strength at streamer head decreases in the spherical development stage,but remains un-changed in the directional development stage,and the density of net charge at streamer head always decreases.The increases of initial discharge voltage and pulse gradient as well as the decrease of DC component will increase the streamer propagation velocity and maximum radius.When the loop inductance is ignored,the streamer causes unipolar bipeak discharge pulse.The spherical stage,the directional stage,the pressboard charging process,and the charging dis-sipation process correspond to the first peak rising edge,the first peak falling edge,the sub-peak rising edge,and the sub-peak falling edge,respectively.The loop inductance causes oscillations in the first peak,and the oscillation frequency and pulse amplitude are approximately linearly negatively correlated with the loop inductance.This study lays a theoreti-cal foundation for revealing the discharge mechanism of oil-paper insulation under transient voltage and has important significance for uniforming the waveform characteristics of discharge pulse.
oil-paper insulationfield-circuit couplingpartial dischargespace chargenanosecond pulsefull current
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维普
