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Ionized field strength on the ground level is one of the fundamental electromagnetic environment parameters of ultrahigh voltage direct current (UHVdc) transmission lines. An algorithm of an upstream boundary element method is presented in this paper to calculate the ionized field on the boundary with a high accuracy. The ionized field is generated and measured in an experimental platform with an HV conductor to a grounded cylindrical corona cage. The relations between ionized field strength and applied voltage, conductor position, and conductor diameter are investigated. Calculations show that the relative error of the ionized field on the HV electrode could be reduced to 0.1% when compared with the analytical solution. Ionized field distribution under the typical ±1100 kV UHVdc transmission lines is also analyzed as the application. [ABSTRACT FROM AUTHOR]

The HVDC and HVAC transmission lines running on the same tower is a promising technology to improve the transmission capacity of an existing corridor. The ions generated by corona discharge of HVDC transmission lines will strengthen the ground-level electric field, which may endanger human exposure. To investigate how the presence of HVAC transmission lines changes the ion-flow field, experiments are carried out on an indoor test model with bipolar dc and three-phase ac lines. The experiment results are then compared with the simulation results. The experiment and simulation results show that the HVAC transmission lines have a shielding effect on the ion-flow field from the HVDC transmission lines running above. Finally, the ground-level electric field and ion current density of the \pm 800–kV HVDC and 500-kV HVAC transmission lines running on the same tower are calculated. [ABSTRACT FROM PUBLISHER]

A modified method based on the optimized charge simulation method (CSM) is used to predict the corona onset voltage and electric field when the space charges due to the corona are considered. Based on the streamer model of corona discharge, space charges generated near the conductors are predicted. In order to calculate the electric field at the conductor surface, space charges are replaced by some equivalent line charges near the conductor. Because of the existence of space charges, the corona onset electric field is changed a little. After a simplified model of actual power transmission lines is introduced with the help of rough coefficient, the corona onset voltage and corona onset electric field are calculated for different types of conductors finally. [ABSTRACT FROM PUBLISHER]