The influence of Airflow on Corona Discharge on Overhead Ground Wire of UHVDC Transmission Line During Lightning

Corona discharge phenomenon around the overhead ground wires produces large amount of ions that can prevent the onset of upward leader on overhead ground wire during thunderstorms. In the present study, simulations on corona discharge on overhead ground wires have been conducted in detail with a two-dimensional geometrical model. During simulation, only positive ions and negative ions are considered with ionization process, recombination process, diffusion and migration movement. A composite electric field has also been applied by thundercloud, downward leader charge and operation voltage of UHVDC transmission lines. Besides, the influence of airflow on corona has also been studied in detail. Simulation results indicate that there’s significant difference of corona discharge between the left and right overhead ground wire and the influence of airflow on corona discharge tend to be less significant as downward lightning leader propagates to some certain extent.

I. Introduction

The height of ±1100kV UHVDC transmission line is commonly around or higher than one hundred meters. During thunderstorm, there’s corona discharge on overhead ground wire which increases its diameter equivalently. The corona discharge on grounding object can affect its lightning attractive ability [1]. The electric field stays almost constant within the boundary of a certain spatial charge area. To build a simplified calculation model of corona discharge, Kaptzov’s assumption was proposed. It assumes that the electric field at electrode surface that corona onset is constant. The thickness of corona charge area is considered as 0. The simplified assumption makes it possible to simulated the corona discharge on the ground during natural thunderstorms.