Research On Contamination Depositing And Pollution Flashover Characteristics Of Post Composite Insulator For UHV Converter Station In High Altitude Area

In China, many HVDC lines have to pass through high altitudes areas, so it isimportant to study pollution characteristics of post insulator in high altitude area. At present,the research mainly relies on natural contamination test, while study on hydrodynamicscharacteristic around post insulator during the contamination process is rare. This papercombined the simulation and natural contamination test, started from the microscopicmechanism and the actual measurement to study pollution characteristics of post compositeinsulator in high altitude area, and carried out artificial pollution test to study DC flashovercharacteristics of post insulator in high altitudes areas. The results have importanttheoretical and practical value.Firstly, this paper created3D model of post composite insulators with a differentstructure and parameters of sheds, secondly, used Fluent to analyze hydrodynamicscharacteristic around post insulator during the contamination process, then separated everyinsulator into up, middle and down three regions, each region was divided into lowersurface and upper surface of big shed, lower surface and upper surface of small shed andinsulator core five parts, at last, calculated contamination particulate collision density ofeach parts of insulator. The results were compared to the result of natural contamination testcarried out at UHV Engineering Technology (Kunming) National Engineering Laboratory.Finally, this paper carried out DC pollution flashover test to study the impact of altitude,SDD, NSDD etc. on DC flashover characteristics of post composite insulators.The conclusions are as follows:(1)The accumulation of pollution of alternating large and small shed designed insulatoris more serious than alternating large and two small shed designed insulator. The reasonableincrease of sheds’ length would improve the level of anti-fouling. In the dry season or inareas with less rain, the contamination of upper surface of post composite insulator is moreserious than the lower surface of post composite insulator. For the same insulator, thepollution would be more serious when the position is lower. Simulation considered that the contamination of insulator core is the most serious while artificial pollution test consideredthat the contamination of small shed is the most serious.(2)When diameter of particles is larger than5μm, the collision density would increasewith the increase of diameter. With the increase of wind speed, the collision densitydecreased first and then increased, the critical point is5m/s.(3)The relationship of DC flashover voltage and altitude of post composite insulatorcould be revealed as: U/U0=1-0.054H. DC flashover voltage decreases with the increase ofpollution degree, SDD and NSDD. This paper recommends up-and-down method forquantitative research, while rise-voltage method could be used for qualitative analysis.