| In order to advance the realization of “Carbon Peak,Carbon Neutral”,it is urgent to build UHV transmission lines to improve the consumption capacity of clean energy.As well as the problem of corona discharge in the process of transmission line operation.Corona discharge will cause power loss and radio interference,which will seriously affect the safe operation of UHV transmission lines.Especially in severe environment such as rainfall,the surface state of conductor is an important factor affecting corona performance.Therefore,the influence of various materials on the discharge of conductor surface under rain conditions is investigated,which is helpful to improve the discharge mechanism of conductor under rain conditions and has important guiding significance for improving the corona performance of high-voltage transmission lines.In this thesis,the positive corona discharge process of HVDC transmission line is studied from hydrodynamic model and particle kinetic model,and the micro processes such as electric field intensity and electron density are explored in detail.The specific research contents are as follows:(1)An improved hydrodynamic model is proposed to simulate the micro physical process of air discharge in two kinds of conductors with different cross-sections under atmospheric pressure.The characteristics of electric field distribution and plasma sheath of different conductors during discharge are discussed.The effects of conductor radius and the number of outer strands on the discharge characteristics are analyzed.(2)Based on the Particle-In-Cell Monte Carlo collision(PIC-MCC)method and the kinetic theory,the 2D3 V particle model of DC corona discharge is established,and the influence of raindrop materials on the corona discharge characteristics under common rain conditions is analyzed.The formation of corona discharge as well as the involved electric field distribution,plasma density,propagation velocity and discharge current are studied.The main effects of raindrop materials with different cone angle,volume and spatial distribution on the surface discharge are obtained.(3)Using PIC-MCC model,the corona discharge of different coating materials under atmospheric pressure was simulated,and the influence of coating thickness and relative permittivity on the corona discharge process of conductors surface was analyzed.The discharge models of smooth conductor and coated conductor are established.The temporal and spatial development of electric field intensity and electron temperature in the process of positive corona are obtained.The influence of coating materials on corona characteristics of defective wire and conductor surface in rain is analyzed. |
