Space Charge Analysis And Equivalent Circuit Model Research On AC Corona Discharge In Transmission Line

AC corona discharge widely occurs around overhead transmission lines,which causes energy loss and changes electromagnetic environment.The research on the process of AC corona discharge and the establishment of the discharge model of AC corona discharge are not only conducive to the optimization of the wires’ form and structure,but also of great significance to simplify the calculation of corona loss and further study of corona discharge.From the view of the combination of micro process and phenomenon of corona discharge,this paper focuses on analyzing and exploring the law of space charge quantity and migration in the process of AC corona discharge.Based on this,an AC corona discharge model is proposed,which conforms to the development process of corona discharge.Finally,the element parameter expression of AC corona discharge model is obtained by mathematical derivation.The main research work of this paper includes:(1)Establish a corona discharge model of coaxial cylinder.Based on the micro process of corona discharge,the process of space charge accumulation is analyzed by considering the micro reactions of charge impact ionization,neutralization and adhesion.According to the different state of space charge distribution,the area outside the conductor is divided into different regions,and the intensity and distribution of space electric field in different regions are calculated by Maxwell equations.(2)Build the corona discharge test platform of transmission line,simulate the corona discharge process of conductor under AC voltage,and design the experimental scheme to measure the waveform curve of space charge,corona pulse current signal and corona loss curve.(3)Through corona pulse current signal and corona loss curve,the validity of space charge waveform curve reflecting space charge change is verified.By analyzing the waveform of space charge quantity and corona pulse current signal,the law of space charge quantity change in the process of corona discharge is obtained.Through the comprehensive analysis of the waveform curve of space charge quantity and corona loss curve,the law of space charge movement in the process of discharge is obtained.(4)Based on the analysis of the space charge quantity and motion law,the phenomenon in the measurement is explained,and the equivalent circuit model of AC corona discharge which accords with the micro law is put forward.By establishing the mathematical model of corona discharge,the quantity change and migration state of space charge per unit time are calculated,and the expression of component parameters in the equivalent circuit model of AC corona discharge are derived.In the end,the model of AC corona discharge is verified by experiments.