Study On Electromagnetic Field And Corridor Optimization Of Quadruple-circuit Transmission Line With Dual Voltage1000kV/500kV On The Same Tower

With the rapid economic development of china, electric Power has become an important force in economic development. In order to solve the characteristics of unbalanced distribution of load demand and energy center in our country to a achieve the goal of energy resource optimizing configuration and ease the power supply tensions in central area. The development of UHV power grid has been imperative. However, with the enhancement of public awareness of environmental protection, the electromagnetic field problem has become a critical restriction for UHV AC transmission project in our country. Because land resources in the east central area are scarce, for saving the cost of transmission corridor and transmission project construction, quadruple-circuit transmission lines with dual voltage1000kV/500kV on the same tower will be taken into considered. In this circumstance, the electromagnetic field under transmission lines will be more complex and more diverse, so an accurate evaluation of electromagnetic field is very necessary.Firstly, three-dimensional electromagnetic field calculation model in which the sag of the transmission line has been considered is established based on the catenary equation that was suspended with equal height. Electromagnetic field measurement of the first UHV-AC transmission line was carried out, the accuracy and effectiveness of the model established in this paper has been verified through the comparison of simulation result and measurement result. Three dimensional distribution and laws of electromagnetic field within a span were studied when quadruple-circuit transmission lines with dual voltage1000kV/500kV on the same tower was erected. Some influential factors which related to the maximum value and distribution of electromagnetic field, such as the structure parameters of conductor, the spatial structure arrangement of phase conductor, the phase sequence alignment, the minimum height to the ground were studied. The result showed that the structure parameters of conductor has little influence to power frequency electric field and magnetic field; the phase sequence alignment and the minimum height to the ground of transmission conductor were the main factors that influence the distribution of power frequency electric field and magnetic field. The principle of the width of transmission corridors was determined, the width of corridor and transmission capacity of unit corridor width were studied when using various transmission combinations to deliver the same amount of capacity, the pros and cons of various transmission combination were compared.