A New Approach to Calculate the Ionized Field of HVDC Transmission Lines in the Space and on the Earth Surface

Corona discharge is a common phenomenon in high voltage transmission lines. The corona space charge arising from HVDC transmission lines is much more significant than that from HVAC lines due to the extended distribution of the space charge, which greatly influences the electric field strength on the ground and in space. A new iterative method has been developed to solve Poisson´s equation for HVDC line systems, accounting for the presence of space charge. The electric field strength can be calculated in the space around the HVDC transmission lines or on the ground. The system can be in homopolar, bipolar or hybrid mode, and can include sky wires or non-corona conductors. The conductors in the bundles are treated individually. The treatment accounts for the different corona onset gradient of positive and negative conductors and for ion recombination in the bipolar zones. Also, the positive and negative ions can possess different mobilities.