Numerical Analysis On Microscopic Process Of Corona Discharge And Ionized Field Of HVDC Transmission Lines

The problem of ionized field caused by the space charge of corona becomes ratherserious for UHVDC transmission lines that due to the fixed voltage polarity. It’s of greattheoretical value to study the microscopic characteristics of corona discharge in order toexplore the and so on which results in the complexity of kinetics rule. A lot of key microparameters related to corona discharge can’t be obtained through experiments as lack ofeffective means for plasma diagnosis. There is no breakthrough on the research ofdevelopment law of corona discharge and to calculate the ionized field of UHVDCtransmission lines. Corona discharge generates a large number of excited particles, ions,free radicals corona mechanism, even a lot of efforts have been devoted. What’ worse,there is no model of corona discharge microscopic physical process which can be usedfor quantitative analysis.In this paper, an improved hybrid model based on fluid dynamics model isproposed to study the corona discharge microscopic physical process. A bar-to-platemodel is established for the calculation of corona pulse current, and for the research ofspace-time development law of corona discharge during the single pulse. A ionized fieldcalculation model is established to discuss the influence of transmission line structurethe relative air density on the ionized field. The main research results are as follows:①For the first time, a hybrid model of corona discharge is put forward for thequantifiable study of microscopic physical process. In this model, the fluid dynamicscontrol equation is used to describe the macro regularity of corona discharge; Theplasma chemical reaction process is used to analyze the generation and dissipationprocess of particles；The Boltzmann equation module provides electron transportparameters and the energy transfer coefficient for fluid dynamics control equation, andchemical reaction rate for plasma chemical reaction module. The validity is verifiedthrough the comparison of single pulse corona discharge waveform and U-Icharacteristic curve②The positive and negative corona pulse forming mechanism is analyzed. Baseon this mechanism, characteristics of electrons (such as electron mean energy, electron density, generation and dissipation rate of electrons) and characteristics of heavyparticle (such as net charge density, rate of plasma chemical processes, element andnumber density of heavy particle) during the single pulse is emphatically analyzed.③The ion flow field calculation model of corona discharge is established basedon the up stream FEM. The validity is verified through the experimental data of theground level total electric field and ion current density. The influence of transmissionline structure on ionized field is discussed, the influence of relative air density onionized field is emphatically analyzed. The calculation result of DC transmission lineshows that it’s essential to check transmission line structure via high altitude and hightemperature area in order to meet the national standard. The calculation result of±800kV and±1100kV DC transmission line on ionized field shows that it’s essential tocheck the transmission line structure when crossing high altitude and high temperaturearea in order to meet the national standard of total electric field strength.