On the corona voltage-current characteristic of unipolar HVDC transmission lines

Abstract

Simplified analytical analysis of ionized fields associated with HVDC transmission lines is possible if it is based on Deutsch's assumption. The resulting voltagecurrent (V-I) characteristic may be conveniently used to calculate the power losses of a HVDC transmission line. However, such an approach has been criticized because Deutsch's assumption is considered invalid for the line-plane geometry. This paper verifies the validity of the V-I characteristic thus obtained by comparing it with numerical results which are generated using a new method developed by the authors, in which Deutsch's assumption is not employed.using Deutsch's assumption. Some authors [3,4] have argued that Deutsch's assumption is not valid for a lineplane geometry even in the absence of wind. Their studies show that the flux lines of an ionized field do deviate from those of the corresponding charge-free field.Since an analytical expression of the V-I characteristic is a convenient form to use in the design of a HVDC transmission line, it is of practical importance to verify the validity of Deutsch's assumption in the absence of wind. In this paper, results generated by using a new numerical method, developed by the authors [5,6,7], are compared with those obtained by employing the analytical method in [2]. The numerical method does not resort to Deutsch's assumption.