Numerical Calculations of Monopolar Corona From the Bare Bundle Conductors of HVDC Transmission Lines

This paper provides accurate numerical calculations of the monopolar corona phenomenon for bundled transmission lines. The corona onset voltage and electric field are known to vary along the circumference of the conductor, as well as with height. After solving for the charge distribution on the conductors at a constant applied potential, the gas discharge criterion is used to evaluate the corona onset voltages and electric fields of every surface in a symmetric bundle of six bare conductors. The fourth-order Runge-Kutta-Gill method is used to solve the corresponding differential equations, presented as an initial value problem with boundary conditions. The corona onset voltages calculated by this method agree with published experimental data on simpler configurations. Finally, the numerical results are discussed in detail for the six-conductor configuration currently used in the construction of Chinese transmission lines, considering two types of conductor.