Simulation of surface charges on dielectrics in ion flow fields

Summary

With the development of Ultra-high voltage DC, the electric field and ion flow around UHVDC lines have raised increasing interests and concerns. The ions generated by the corona will accumulate on the dielectric around the UHVDC lines and significantly affect the electric fields. Therefore, it is necessary to study the computing method of surface charges on dielectrics in ion flow fields. In this paper an approach based on finite difference method is presented. The simulation can be divided into three main parts: the electrostatic field, the ion flow field and the modification of polarization. While calculating the electrostatic fields, the finite different method is used to solve the Laplace’s equation. Based on the electrostatic field, ion flow fields and space charge density could be obtained by the upwind difference method. The boundary condition on the surface of the dielectric where surface charges accumulated is that when the accumulation of ions reaches saturation, the normal component of the gas-side electric field En is 0. Through this simulation, the distribution of surface charges along with the electric field nearby can be obtained. The simulation results are in accordance with experiment results, which testifies the validity of this simulation. Results shows that electric field strength is a key factor in the accumulation of surface charges. With this computing method, electric fields around the UHVDC lines could be obtained when there are dielectrics nearby, which is useful for the insulation design.

Additional informations

Authors

ONDREJ, Jungqvist, PERRIER

Keywords

surface charge, dielectric, ion flow field, simulation