Study On Electromagnetic Characteristics Of Plasma Corona Discharge Based On Pin-plate Model

With the wide application of Ultra High Voltage Direct Current transmission,the process of high-voltage transmission faces more severe problems.At the tip of the equipment in contact with air,air corona discharge occurred,resulting in electromagnetic interference and insulation performance damage of high-voltage transmission equipment.Therefore,understanding the discharge mechanism of the corona discharge and studying the electromagnetic characteristics of the positive and negative corona discharge with the development of discharge are of great significance to the safe operation of the high voltage direct current transmission equipment.The corona discharge has the polarity effect,which corresponds to the different discharge phenomena under different polarities.The characteristics of various partial discharge models were studied.Based on the principles of the hydrodynamics and plasma chemical particle reaction,a two-dimensional axisymmetric model of fluidplasma chemical reaction was established.The corona discharge process under different polarities of the positive and negative was analyzed.And the spatial distribution,transport process and electromagnetic characteristics of the charged particles were studied.The main contents of this thesis are as follows:(1)Based on the basic theory of the gas discharge,a fluid-plasma chemical reaction model was established.The plasma chemical reaction equation was added to the classical fluid dynamics model.The reasonable boundary conditions and discharge parameters were applied.(2)According to the intensity of discharge,the corona discharge characteristics of positive polarity were divided into electron avalanche property and streamer property in the development process.The air gap is gradually broken down with the process of discharge and the secondary electrons in the process of the positive ion collision in the cathode lead to higher current.(3)The discharge characteristics of the corona discharge under negative polarity were studied.The discharge has periodic regular pulse waves.The rapid generation of electron avalanche leads to the increase of current.And the continuous increase of voltage results in the non-pulse discharge.It is because the rapid accumulation of negative ions weakens the ionization reaction,and the secondary electrons cannot be formed to stop the discharge.(4)The distribution characteristics of the spatial electric field and important particles in the corona discharge under different polarities were studied.The results show that when the voltage intensity is low,the number of O4+ ions and O2+ ions in the axial discharge area is the main position of positive ions.And the number of O2-ions is the largest among negative ions.With the increase of the voltage,the number of N2+ ions in the positive ions begins to increase and the order of O2-ions is still the largest.(5)The pin-plate gas discharge experimental platform under atmospheric pressure was built.And the voltage and current waveforms reflected in the oscilloscope was compared with the global pulse current in the simulation results under different voltage intensities,which verifies the correctness of the built model.