Analysis of Corona Losses on DC Transmission Lines: I - Unipolar Lines

Theoretical calculation of corona losses for practical unipolar dc transmission line configurations presents considerable difficulty because of the nonlinear nature of the equations describing the space-charge fields. The application of numerical methods to obtain solutions of practical interest is discussed. One of the difficulties in the analysis of space-charge fields is the determination of the actual charge distribution around the conductor in the corona. A numerical iterative method of computing this charge distribution is presented. The method is applicable to any general configuration for which the space-charge-free field can be calculated. The line- to-plane configuration is considered. A method of including the effect of conductor surface irregularities in the theoretical calculation of corona losses is outlined, and it is suggested that, by the same method, Popkov´s formula may also be modified to make it applicable to lines with practical transmission-line conductors. Calculations by the method of analysis developed as well as by the modified Popkov equation are compared with experimental results.