| The facts that there is imbalance between energy resource distributions and between productivity developments and the requirement for very rapid economic development in China necessitate the construction of the ultra-high voltage (UHV) grid. The evaluation for electromagnetic environment of the UHV transmission lines is a subject of great importance because of its high voltage order. The corona discharge, as an inevitable phenomenon from the UHV transmission lines, will bring about audible noise, radio interference, corona loss and so on, which influence the environment and power system operation negatively. Therefore, researches on the corona of the UHV transmission lines are of both important theoretical significance and practical application values.±800 kV UHVDC transmission lines will be developed in Shandong province according to the long-term plan. Due to the dry, rainless and dusty climate environment in Shandong district, it is easier to form burrs on the surface of UHVDC transmission lines, which intensify the occurrence of corona discharge. To this end, the electric field distortion and electromagnetic interference of conductors with burr tips are studied in this paper. First, the introduction for the composition and characteristics of UHVDC, the characteristics of electric field on DC transmission lines and the calculation methods of electric field strength on the surface of DC transmission lines are given. Second, considering the burr as ellipsoid or cone, tip discharge by burrs of different sizes is modeled. Based on these two models for the burrs, the distributions of electric field around the tip are explored and the influence of burrs on electric field is also analyzed. Third, under different cases, where the burrs are in different models, are of different material constitutions, and are located at different position on the surface of the transmission line, the corona discharge due to burrs are simulated and analyzed, systematically. The simulations by using the maxwell code show that for the burrs with a fixed position on the surface of the transmission line the dependence of maximum field strength around the wire on the shape of the burrs presents a certain regularity, however, the maximum field strengths produced by the burrs with a fixed shape and located at different position on the surface of the transmission line are distributed in different regions around the transmission lines. The burr significantly promotes the occurrence of corona discharge when the materials of burr contain the electrolytes. Finally, the electromagnetic interference induced by corona discharge are analyzed, and the corona radiation field as a respective function of the frequency, horizontal distance, line height properties and wire radius are calculated in detail by means of MATLAB code.The analyses and results presented in this paper on corona phenomenon of UHV transmission lines are useful for the establishment and revision of electromagnetic environment standard of UHV grid.
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