Study On Radio Interference Of AC Ultra High Voltage Transmission Lines

Radio interference(RI) is one of important parameters to determine the configuration of tower and conductor, which affect construction cost of power grid. Ultra high voltage (UHV) AC transmission lines have higher voltage which results in a more complex electromagnetic environment problem. Thus study on RI of UHV line is of very important theoretical and practical significance.By analyzing surface electric field intensity of conductor, the paper induced algorithm Markt-Megele method and successive image method. And taking UHV double-circuit line for example, algorithm was validated and influencing tendency of line parameters on surface electric field intensity was then analyzed.Excitation function is an important reference method of RI calculation of UHV transmission lines. The paper describes generation, distribution and progression of corona current. Implication of Excitation function and calculation procedure of RI is also presented. Example validation proved the correctness and reliability of the program based on excitation function with calculation error less than 5%.Separated number, bundle spacing, cross-section and height of conductor are important factors affecting RI. And these factors were systematically investigated. The results indicated that: the interval of RI is about 4dB every single sub-conductor decreasing, and the tendency of RI changing with the bundle spacing exhibits a U-form distribution. For 8×630mm~2 conductor, RI is lowest when bundle spacing is 30cm among all studied ones. RI decreased by about 1~2dB when cross-section increases. The height of conductors has little influence on RI. The increasing soil resistivity will accelerate corona attenuation, thus RI decreases as a result.