Calculation of the Spatial Charge Distribution in Ultra-high Voltage
Direct Current Transmission Lines Based on Dilute Species Theory
Abstract
The ion current generated during the operation of UHVDC (Ultra-high
Voltage Direct Current) transmission lines has an increasingly prominent
impact on the electromagnetic environment. At present, electric field
line method and finite element method are commonly used to achieve fine
steady-state solution of ion flow field, but the dynamic process of
corona discharge is not analyzed. Therefore, based on the dilute species
theory, the real-time motion state of charge is considered, and the
behavior law of ions in complex flow field and electric field is
emphasized. The effect of wind speed on space charge distribution is
also analyzed. It provides reference for the electromagnetic environment
prediction, control, and evaluation of UHVDC transmission projects. The
results show that the microscopic process of positive and negative
corona discharge is different. It also shows that the two have different
mechanisms for maintaining self-maintained discharge. According to the
established ±800kV UHVDC transmission line model, the maximum ion
current density near the ground is 32.62nA/m2. Affected by the wind
speed, the ground ion current density on the downwind side gradually
decreases, while the upwind side gradually increases. When the wind
speed is greater than or equal to 3m/s, the ground ion current density
on the downwind side decreases to 0.