Study On The Model And Impact Factors Of Boundled Conductors And Parallel Composite Insulator Strings Icing

Although the experts at home and abroad have done the massive research on the mechanism of transmission lines icing at present, the research work are limited to single cylinder and insulator, to the icing procedure of bundled conductor and parallel insulator strings which are extensively used in the UHV DC and AC transmission project, there is still lack the corresponding research. Thus, the research work on the flow field and collision performance of the bundled conductor and parallel insulator strings, and investigate work on the impact factors of transmission lines icing in field, which can not only make us understanding the mechanism of transmission lines icing more thoroughly, but also provide valuable reference for the research work of anti-icing and de-icing.Therefore, the thesis is of great realistic significance and theoretical value. The gas-liquid tow-phase flow field mathematic model of the transmission lines icing procedure is proposed based on fluid mechanics. The flow field performance around the bundled conductor and parallel insulator strings are analyzed. The collision performance of the windward surface of bundled conductor and parallel insulator strings are researched in this thesis. The icing procedure of the parallel insulator strings is simulated in the artificial chamber, and the impact factors of conductor structures on transmission lines icing are investigated in field. The principal research works about this thesis are as follows:According to the aerodynamics, the gas-liquid tow-phase flow field mathematic model of the transmission lines icing procedure is established, and the calculation method of local collision coefficient is proposed. The gas-liquid tow-phase flow field around the bundled conductor in the conductor icing procedure is simulated by CFD software Fluent based on the mathematic model. The characteristic of the air velocity field along windward and leeward of the windward conductor in 2-bundled conductor is analyzed. The local collision coefficient of the windward surface of the 2-bundled conductor is researched under different wind velocity (v0), liquid water content (LWC), conductor diameter (Dc), media volume diameter (MVD) and split spacing (?L) conditions. The simulated results show that the wake flow of the windward conductor has a great influence on the local collision coefficient of the windward surface of the leeward conductor, and this impact will be diminished gradually with the increase of the split spacing. The influence of v0, LWC, Dc, MVD,?L and angle of attack on the local collision coefficient of the windward surface of the leeward conductor is analyzed, and the physical characteristics of the wake flow of the windward conductor is researched.The gas-liquid tow-phase flow field around the parallel insulator strings in the specimens icing procedure is simulated. The simulated results show that the distribution of the velocity and volume fraction field of the water droplet near the surface of the windward is greater than the leeward of the specimens, and to the near each other side of the parallel insulators, the velocity and volume fraction field near the surface of the specimens will influence each other. The equivalent diameter of the insulator is proposed, and this equivalent model is verified according to the comparison with the reference value. The collision performance of the single and parallel insulator strings are researched based on the equivalent model under different climate conditions and separation distance, the simulated results show that the collision coefficient of the single and parallel insulator strings are different under different climate conditions and separation distance. The icing process of the parallel insulator strings are simulated in the multi-function artificial climate chamber of Chongqing University. The test results show that the wind velocity has great influence on the icing episode of the parallel insulator strings, the ice thickness discrepancy of single and parallel insulator strings is small while wind speed becomes small, but the icing episode of the parallel insulator strings will become severe than the single one while wind speed increases.The relationship between height and icing thickness of tower and cylinder is investigated in Xuefeng Mountain icing observation station, the altitude correction coefficient of conductor and tower icing thickness of the investigated area are proposed. The relationship between diameter and icing thickness of cylinder is investigated in Xuefeng Mountain icing observation station and other areas in Chongqing and Hubei, according to analysing the ice thickness measured in field and the historical data of Chongqing University, the diameter correction coefficient of conductor icing thickness of the investigated area are proposed.