| The surface conditions of the conductors have great influence on corona discharge and its produced audible noise,radio interference,resultant electric field and so on in the extra and ultra HVDC transmission lines.Due to the serious environmental pollution in China,HVDC conductors operating in contaminated areas may absorb a large amount of contamination,which seriously affects its surface conditions.This dissertation studied the mechanism of the variation of HVDC conductors surface conditions under contaminated environment through theoretical and experimental approaches.This work will be of great significance for perfecting the contamination mechanism of the DC conductors and forecasting the contamination characteristics of the DC conductors more reasonably.Firstly,an artificial accelerated contamination accumulation system was built.The electric field,the component,concentration of the contamination and the contamination accumulation time can be controlled in the system in order to carry out the experiments flexibly.Secondly,contamination characteristics of the DC conductors in the free of charge electric field was investigated.Based on the analysis of the polarization characteristic of single particle and the interaction between particles,accumulation theory of one particle and more particles on the surface of DC conductors was established.The experimental phenomena of the parallel chains distribution shape of particles and the accumulation shape of particles at a point similar to a cone on the surface of conductors were obtained respectively.At last,contamination characteristics of the DC conductors in the ion flow field was investigated.The charging and motion characteristics of single particle were studied.Based on the analysis of the surface morphologies of conductors under different positive DC corona discharge intensity,the experimental law of the corona discharge may suppress the formation of contamination on the surface of conductors was obtained. |
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