A Wave-Front-Time Dependent Corona Model for Transmission-Line Surge Calculations

Abstract

For transmission-line surge studies, the inclusion of corona discharge due to high voltage surges is important as well as the inclusion of frequency-dependent effects. Because the charge-voltage (q-v) curve of a lightning surge is different from that of a switching surge, a corona model should reproduce different q-v curves for different wave-front times. The present paper proposes a wave-front-time dependent corona model which can express the dependence by a simple calculation procedure as accurately as a rigorous finite-difference method which requires an enormous calculation time. The simplicity enhances the implementation of the corona model into a line model, because a large number of the model is to be inserted into the line model by discetization. The calculated q-v curves by the proposed method agree well with field tests. This paper also proposes an efficient method to deal with nonlinear corona branches in a distributed-parameter line model using the trapezoidal rule of integration and the predictor-corrector method.