| Roof insulator is an important high-voltage equipment installed on the top of the train,and is one of the key equipment to ensure the safe and stable operation of the train.Because the operation environment of the roof insulator is very bad,and it is exposed outside the vehicle body for a long time,bearing the combined effect of high-speed air flow,impulse over-voltage,complex driving environment along the line and other environmental factors,which is very easy to cause partial discharge and other accidents.With the rapid development of the economy of China and the continuous deterioration of the environment,haze weather has become an important challenge for the operation of high-speed trains.Due to the severe pollution on the surface area of the roof insulator under the bad weather environment such as haze,pollution flashover accident is very easy to occur,which leads to the damage of the on-board equipment of Electric Multiple Units(EMU),the short circuit and power failure of Overhead Connecting Structure(OCS),and even leads to the severe accidents such as OCS disconnection,explosion of on-board equipment of EMU,which brings great challenges to the safe and stable operation of high-speed trains.This project takes the roof insulator of EMU as the research object,conducts simulation calculation of the air flow field of the roof insulator in high-speed running state with the help of software Fluent,analyzes the influence law of the air flow distribution on the pollution characteristics of the insulator,and conducts the pollution flashover test of the roof insulator of EMU combined with relevant standards.On this basis,different antifouling flashover coatings are applied to insulators,and the insulation performance of different antifouling flashover coatings is tested.In addition,the model simulation analysis is used to study the antifouling insulator of the new structure,the new structure insulator is made in cooperation with the relevant manufacturers,and they are tested and analyzed,and the method and strategy of antifouling structure optimization of the insulator are put forward.The research results of this paper provide theoretical basis and experimental data for the research on the improvement of roof insulator structure and insulation capacity of EMU in high-speed air flow environment.The results show that the pollution distribution of roof insulator is regional in high-speed airflow environment,and the pollution is most serious in windward and leeward areas.When the surface area of the vehicle roof insulator is polluted,the probability of flashover will increase,and the flashover voltage will gradually decrease with the increase of the equivalent salt density content in the pollution.The coating method can significantly improve the the surface hydrophobicity and the insulation performance of insulators.However,the flashover voltage will be even lower after the coating is seriously worn and damaged than when it is not coated,and the insulators face higher flashover risk.In the structural optimization simulation of the insulator,it is found that the surface electric field distortion is the smallest when the upper inclination angle of the umbrella skirt is 6° and the lower inclination angle is 0°,and the air flow characteristics and insulation performance are well guaranteed when the distance between the umbrella skirts is 20～40mm.For this reason,the new structure of insulator mainly chooses the upper inclination angle of the umbrella skirt to be 6°,the lower inclination angle to be 0°,the distance of the umbrella skirt to be20～40mm,the combination way of a large and a small umbrella skirt and the structure without the umbrella ridge.The pollution flashover test of the new insulator shows that the pollution lightning voltage is improved greatly. |
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