Calculation And Study On Influence Factor Of UHVDC Transmission Lines Synthesis Electric Field

The UHV transmission is the inevitable trend of power grid development in the context of China’s national conditions. The UHV DC transmission project is one of the main ways of UHV power grid construction. At present, China’s Xinjiang-Anhui ±1100k V UHVDC transmission project has officially started construction, a number of ±800k V UHVDC transmission lines have been built and put into operation. Therefore, it is urgent to actively carry out research on the technology of UHVDC transmission.In this paper, the effect of electric field on the electric field caused by corona discharge in UHV DC transmission line is studied. Firstly, based on the FEM, the 2D model and 3D model of UHV DC transmission lines are built, and the nominal electric field is calculated, and the calculation accuracy and efficiency are improved by some improvement measures. Then summarizes the empirical formula of the United States EPRI, obtains the electric field below the lines, and analyzes the advantages and disadvantages of the two models and the scope of application. Finally, an example verified the correctness of the algorithm in this paper.Based on the proposed algorithm, mainly to study the synthesis of ground electric field with the height of contact wire, wire electrode spacing, division of wire spacing and root number, wire surface condition, humidity, barometric pressure and elevation changes of distribution, and put forward the suggestions to reduce the synthesis of ground electric field. Research shows that: the ground synthetic field with the wire electrode spacing, wire surface rough degree, altitude height increase and increase, with the wire height, absolute humidity increases decreases; reduce the splitting number of wires and reduce the wire bundle spacing can reduce the synthesis of electric field; guide line of highly effect is the most significant, the relative humidity has little effect on the synthetic field.In addition, the distribution characteristics and influencing factors of the mixed electric field on the ground are studied in this paper when the DC circuit and the AC line are in parallel or in the same tower. Research shows that: either in parallel or in the same tower erection, mixed field were greater than a single field; AC and DC transmission lines in the same corridor set up and need to comprehensive evaluation of the economic and environmental value, to determine the close distance appropriate, not only can reduce the mixing intensity and can maximally save corridor width; AC and DC transmission lines on the same tower erection, the distribution law of the mixed electric field is consistent with the distribution of the electric field in the lower circuit; It is advantageous to reduce the intensity of the mixed electric field on the ground that the AC conductor is placed in the lower layer of the direct current conducting wire and appropriately increasing the height of the AC line to the ground.