Research On Influence Factors And Calculation Method Of DC Corona Onset Voltage

In China, the energy resources is against the productive forces development, the base of energy in the west is far away from the load centers in the east, so the transmission systems with long distance and large capacity should be established. Ultra high voltage technology has the advantages of large capacity, long distance and low loss, however, with the rapid development of ultra high voltage, a series of electromagnetic environment problems has brought up, the corona discharge is one of the main causes. This paper, firstly, have analyzed the production and disappearance of the charged particles in the process of corona discharge, and the movement of the charged particles in the applied electric field. And then,have analyzed the calculation method-theory formula method, a new method for calculation of D.C. corona onset voltage in bundle conductor is proposed in this paper with neglecting the distortion of the electric field by the space charge. First of all, finding the direction in which the discharge in bundle conductor most likely to occur and geting the electric field distribution in the direction; then using the found electic field distribution and the radius of the wire in actual condition as the electic field distribution and radius of the wire respectively in the line-cylinder cylindrically symmetrical structure; Finally deducing the onset voltage from the derived onset criterion of the line-cylinder cylindrically symmetrical average discharge. To prove this method is effective, experiment is disign to measure the onset voltage of2-split、4-split and6-split bundle conductor, the radius of each smooth wire is1.5mm. The consistency is found good after the comparison of the result derived from the new method and the data found in the experiment. Finally, have carried on the DC corona experiment under the single wire-cylinder structure to analysis the influence of the atmospheric conditions and the conductor surface conditions, the results show that the corona characteristics of the copper and stainless steel materials are almost the same, and the insurface conditions have greater impact on negative corona than on positive corona.