Simulation study on the pollution accumulation of the porcelain insulator in a wind tunnel under direct-current composite electric field

摘要

A direct-current (DC) composite electric field is formed because of corona discharge on transmission lines. This field facilitates particle charging in the atmosphere. The particles charged by such a field are influenced by DC electric force, which affects their motion toward and deposition on insulators and eventually results in variations in the pollution characteristics of DC line insulators. Simulating the effect of a composite electric field near a conductor on the insulator pollution of a DC line is crucial for preventing pollution. In this paper, a threedimensional simulation model was developed for simulating the pollutant accumulation on an insulator string under a DC composite electric field. This model was also used to simulate the ion flow, particle charging, fluid dynamics, and kinetics and collision-adhesion properties of charged particles under a DC composite electric field. In the electrical submodel, the space charge density and ionic current density on the outer surface of insulator pins and caps were used to calculate metals' charge and their floating potential. A charging submodel was developed that embodied the contributions of the electric field intensity and the space charge density of the composite field to the pollution particles' charging in motion. The pollution accumulated on the insulator strings was simulated at different values of various factors, such as conductor voltage, ion flow intensity, and airflow velocity. The simulation results and analyses of the relationship between the factors above and insulator pollution characteristics indicated that a specific composite electric field resulted in the highest pollutant accumulation on the insulator string. The pollutant accumulation on insulator sheds' lower surface increased and decreased with the weakening of the ion flow field when the nominal electric field near the insulator string was excessive and most favourable for polluting, respectively.