Simulation Study On The Contamination Accumulation Of The Porcelain Bell Insulators

In recent years, external insulation flashover accidents occur frequently on the power transmission equipments of electrical system and caused serious harm. Bell-type insulators are widely used in high-voltage overhead transmission lines, despite its relatively large creepage distance and high voltage grade, its structure under furrowed surface makes it easy to plot contamination, adding its worse self-cleaning ability, both lead to flashover accidents very easily under certain conditions. Therefore, the study of the contamination properties of bell-type insulator, to some extent, has very important significance for the dynamic monitoring of the amount of the insulator surface contamination and prevention of pollution flashover. At present, domestic and foreign scholars mostly make researches from the perspective of the insulator surface leakage current, arc flashover characteristics of development in artificial tests, few study on the insulator contamination characteristics.The mechanical mechanism of the contamination on insulators were analyzed and the exploratory criterion for particles depositing on the insulator surface were also obtained. The characteristics of the contamination of the insulator at different DC voltage level in the school wind tunnel test has been discussed, and established a simulation model of the wind tunnel experiment using COMSOL Multiphysics simulation software, the simulation results were compared with the wind tunnel experiments to verify the reasonableness of the proposed criterion and deposition simulation method.The natural contamination characteristics of insulators were achieved by simulation in which the DC electric field analysis using a steady-state simulation, alternating electric field using frequency domain analysis, the impacts of wind velocity, particle size, type of voltage on insulators and other factors on natural contamination characteristics of insulator were analyzedThe results show that: The simulation results of contamination of the insulator in the wind tunnel are in good agreement with the experimental results, indicating that the sediment criteria proposed and the simulation method adopted by the paper is reasonable. In the natural contamination condition, thethe overall surface of the insulator deposition rate increases with the increasing of wind speed, and has a "saturation" property; the deposition rate increases basically linearly with the increasing of particle diameters; insulators in DC、AC voltage and uncharged cases, the role of wind speed increasing the deposition rate is "similar"; as the wind speed increases, the relative amount differences of pollutants on insulator sheds under DC Voltage, AC Votage, and with no charge gradually decreases, the amount differences of accumulated filthy particles on the top, bottom and along the sheds corresponding with the surface of the insulator gradually increases; overall deposition rate of filthy particles under DC Voltage is greater than AC voltage, and the latter has a considerable deposition rate compared with the case of no charge; the deposition rate on the sheds of lower-Voltage end and intermediate sides of insulators is higher for top surface than bottom side, deposition rate on surface of higher-Voltage end has a opposite trend; particle size affects the contamination characteristics more serverly than wind velocity; under the same wind velocity, filthy particles deposition rate differences between under DC Voltage and under AC Voltage and with no charge becomes widen as particle size increases.