A Dynamic Capacity Increase Calculation Model For Overhead Transmission Lines Under Multi-Factor

The power consumption load is increasing gradually with the continuous and rapid increase of the national economy, so how to enhance the current capacity of overhead transmission line has real economy significance. The line's current capacity depends on its machinery, thermodynamics, and electromagnetism characteristics remarkably. So the research on the correlated characteristics of transmission lines becomes a prerequisite for the research on how to enhance its current capacity.The temperature of conductor can be calculated by the steady-state heat transfer model. The stress of steel core and aluminum wire can be gotten by the mechanical model, and the power loss in per unit length in each layer of the conductor can be calculated by the electromagnetic model without considering the temperature difference between the steel core and aluminum wire. The temperature difference between the steel core and the surface of the conductor can be calculated utilizing the power loss mentioned above in the radial conduction model.In this thesis, on the base of the research on the characteristics of overhead transmission lines and the analysis on the individual models together with couple relationships of related parameters, the uniform calculation model was built, and the relationship between the line's current capacity, surface conductor temperature, stress of steel core and aluminum wire, AC resistor, temperature rise, sag of conductor, etc. were obtained. The concept of dynamic capacity increase of transmission line was proposed, and a graphical user interface met a demand of this thesis was designed using GUI. In this thesis, during the calculation of AC resistance, the elongation of each layer due to stranding was considered. During the calculation of mechanics, the primary elongation of the conductor was taken into consideration. The algorithm in this thesis is superior to the traditional arithmetic for considering the influence among each individual model.The research is of some reference value for the operating analysis of transmission lines under high temperature as well as the increasing of the line's current capacity.