Simplified approach of maximum electric field distribution on the ground near HVAC-HVDC shared tower transmission lines

This study extends the superposition method proposed by the Electric Power Research Institute to calculate electric field distribution on the ground near high voltage alternating current-high voltage direct current (HVAC-HVDC) shared tower transmission lines under ultra high voltage (UHV). Maximum electric field on the ground can be easily superposed by electric field when two circuits act separately, and when one circuit acts, thhe other circuit is regarded as ground wires. The ac field is calculated by method of images. The dc field is calculated by a finite element method (FEM). A precise time-domain FEM is used to calculate the hybrid electric field for comparison. Dispersion between results of superposition and time-domain FEM confirms that the superposition method is less time consuming and can satisfy engineering precision.