The Impact Of Aerosols On The Ionized Field Of HVDC Conductors In A Cylindrical Corona Cage

In recent years,the increasingly development of industrialization and urbanization in China has led to the gradual deterioration of t he atmospheric environment.Severe air pollution and haze happened frequently.The suspended aerosols in the vicinity of transmission lines and the aerosols deposit on the surface of the conductors may change the surface conditions of the conductors and affect the corona characteristics.Consequently the electromagnetic environment around the line will become more complex.In order to ensure the reliable operation of HVDC transmission lines under the influence of aerosols,the impact of aerosols on electromagnetic environment of HVDC lines has become an emerging research issue.However,the existing research of domestic and foreign scholars is still far from enough.In this paper,the effect of aerosols on the ionized field of the direct current wire was studied in two aspects by using the coaxial cylindrical electrode.Firstly,an experimental device was designed to simulate the atmospheric conditions with the existence of suspended aerosols.The influence of aerosols of different mass concentrations on the ionized field of HVDC conductors were investigated.Secondly,a controllable accelerating contamination depositing method was proposed and the corona characteristics of conductor with different contamination conditions were studied.This paper calculated the ionized field based on the analytical solution of the direct current electric field in the cylindrical coordinate system and obtained the influence of the structural parameters on the electric field strength around the conductor.The experiment platform of coaxial cylindrical electrode was designed and manufactured based on the calculation results.Suspended aerosols were produced by burning incense in a square plexiglass box.It's known from the study on the influence of incense aerosols of different ma ss concentrations on the ionized field of positive and negative polarity HVDC conductors that,before the corona began,the incense aerosol mass concentration had little effect on the DC electric field.After the corona began,the electric field strength i ncreased and the current density decreased when incense aerosols increased.Calculation indicated that the charged aerosol density increased while ion density decreased more serious when incense aerosols increased.Because of the reduced equivalent mobilit y,more space charges suspended in the air,increased the measured electric field strength;less space charges migrate to the corona cage,decreased the measured current density.The controllable accelerating contamination depositing method proposed in th e present paper was achieved by introducing a controllable ionized field.The study of the ionized field of the HVDC conductors with different contaminations showed that the intensity of corona discharge and the electric field strength were related to the conductor surface conditions.The corona discharge was suppressed and the electric field strength on the ground electrode was decreased when the surface condition of the conductor was improved;the corona discharge was enhanced and the electric field strength on the ground electrode was increased when the contamination condition was not uniform at different positions of the conductor surface;severe streamer coronas appeared when the conductor surface was porous and fluffy with cones existing at times,the electric field strength on the ground electrode were also increased obviously.